Dermoscopy of Cutaneous Neoplasms in Skin of Color – A Systematic review by the International Dermoscopy Society “Imaging in Skin of Color” Task Force

Abstract

Over the last few decades, dermoscopy has been showed to facilitate the non-invasive diagnosis of both benign and malignant skin tumors, yet literature data mainly comes from studies on light photo-types. However, there is growing evidence that skin neoplasms may benefit from dermoscopic assessment even for skin of color. This systematic literature review evaluated published data in dark-skinned patients (dermoscopic features, used setting, pathological correlation, and level of evidence of studies), also providing a standardized and homogeneous terminology for reported dermoscopic findings. A total of 20 articles describing 46 different tumors (four melanocytic neoplasms, eight keratinocytic tumors, 15 adnexal cutaneous neoplasms, seven vascular tumors, four connective tissue tumors, and eight cystic neoplasms/others) for a total of 1724 instances were included in the analysis. Most of them showed a level of evidence of V (12 single case reports and six case series), with only two studies featuring a level of evidence of IV (case-control analysis). Additionally, this review also underlined that some neoplasms and phototypes are underrepresented in published analyses as they included only small samples and mainly certain tones of “dark skin” spectrum (especially phototype IV). Therefore, further studies considering such limitations are required for a better characterization.

Introduction

Cutaneous neoplasms are among the most relevant diseases in dermatologist’s clinical practice as they may cause significant issues, ranging from aesthetic/functional problems to fatal outcomes, hence a timely diagnosis is of utmost importance [1,2]. In this regard, over the last decades, dermoscopy has been showed to be helpful in assisting the early recognition of both benign and malignant skin tumors, mainly in fair-skinned patients [1,2]. However, although some cutaneous neoplasms are less frequent in skin of color (Fitzpatrick’s phototypes IV–VI) as the result of photoprotection provided by the higher melanin content, there is growing evidence that skin tumors may benefit from dermoscopic assessment even for darker phototypes [3]. This is of relevant interest as clinical diagnosis of such lesions may be particularly challenging in dark-skinned patients due to the lack of some clues, such as lesion shade or surface changes (e.g., pigmentation and telangiectasias) [3,4].

This review by the International Dermoscopy Society (IDS) Task Force on “Imaging in Skin of Color” systematically evaluated for the first time literature data on dermoscopy of both benign and malignant cutaneous neoplasms in skin of color, also attempting to correlate reported dermoscopic terminology with a standardized methodology.

Materials and Methods

This systematic review was performed in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and MetaAnalyses) guidelines. A search of the papers published up to 30^th June 2022 was carried out through the PubMed electronic database with the use of the following search terms: “dermoscopy” OR “epiluminescence” OR “dermatoscopy” AND “skin of color” OR “dark skin” OR “black skin” OR “ethnic skin” OR “dark phototype” OR “african skin” OR “indian skin”. Titles and abstracts were screened by two independent reviewers to identify articles reporting dermoscopic findings of both benign and malignant skin tumors; papers on mucosal and nail neoplasms were not considered and non-English articles, reviews, personal opinions/editorials and duplicates were excluded. A manual search was also carried out by assessing the reference sections of all significant studies or reviews on the topic.

Articles considered not relevant and those not mentioning dermoscopic structures according to specific tumor were excluded after full-text reading. Only articles specifically dealing with Fitzpatrick’s phototypes IV–VI were included. If information on the skin phototype was not provided, decision on inclusion was made based on a title/abstract/full text showing that the manuscript concerned “dark skin” or “skin of color” and for single cases also according to the attached figures. We also included papers from African, Indian subcontinent, and Caribbean countries as most of patients from these areas belong to IV–VI skin phototypes. Of note, studies grouping light and dark phototypes with no specific subanalyses were ruled out.

All of the retrieved studies were classified based on standard definitions for diagnostic accuracy studies [5,6] and their level of evidence was assigned according to The Oxford 2011 Levels of Evidence [7]. Dermoscopic findings, histopathological background (if available), dermoscopic setting (polarized vs non-polarized/magnification degree), skin type of the patient (if specified), and number of cases were assessed and summarized. Additionally, standardized terminology based on the IDS dermoscopic criteria for cutaneous neoplasms validated for skin of color was specified for each dermoscopic finding reported in the literature [8].

Results

The initial PubMed search yielded 1287 publications which were screened for relevance to the subject of review, while 10 studies were added after additional reference screening. A total of 29 items were admitted for full-text reading after title and abstract screening and excluding duplicates. Of these, nine papers were ruled out according to the exclusion criteria, with final selection of 20 articles for the review process. Figure 1 shows the flow chart summarizing the study selection procedure.

Figure 1.

PRISMA flowchart displaying the selection process for study inclusion in the systematic review

The full-text review included six single case-reports, 12 case-series, and two case-control studies, thus a proportion of 10% of the studies showed a level of evidence of IV, while the rest of the studies displayed a level of evidence of V. Fourty-six different tumors were evaluated (also considering relevant subtypes with clinical/dermoscopic peculiarities), including four melanocytic neoplasms, eight keratinocyte tumors, 15 adnexal cutaneous neoplasms, seven vascular tumors, four connective tissue tumors, and eight cystic neoplasms/others; a total of 1724 instances were retrieved. Table 1 displays the number of studies and total number of included patients for each condition.

Table 1.

Total number of studies, patients and prevalence of standardized dermoscopic findings of cutaneous tumors in skin of color.

Tumor	Total number of studies	Total number of instances [instances with dermoscopy prevalence data]	Dermoscopic findings* (total prevalence)**
Melanocytic neoplasms
Melanocytic nevi
Acral melanocytic nevi	1	396 [396]	Common findings: -
Blue nevus	1	4 [4]	Common findings: Structureless, blue (100%)
			Less common findings:
Melanocytic nevi (not considering specific sites or histological types)	3	755 [755]	Common findings: Color: brown (76%)
			Less common findings: Lines, reticular (48%); Black color (20%); Structureless (16%); Lines, reticular (10%); Clods, small, round or oval (7%); Lines, reticular/structureless (7%); Grey color (7%); Blue-gray color (7%); Blue color (6%); Clods, small, round or oval + lines, reticular (3%); Lines, reticular + structureless (3%); Clods, small, round or oval/lines, reticular (3%); Clods, small, round or oval + structureless (1%); Lines reticular/clods, small, round or oval (1%); Pseudopods, circumferential or lines, radial, circumferential (0.6%); Red color (0.4%); White color (0.3%)
Melanoma (acrolentiginous, excluding nails)	2	9 [9]	Common findings: Lines, parallel, thick, on the ridges (100%); Structureless, brown, blue, black (89%); Lines, parallel, short, crossing ridges (51%)
			Less common findings: Erosion/ulceration (22%); Structureless zone, blue (11%); Irregular clods, small (11%); Lines, radial (always at periphery) (11%)
Keratinocytic tumors
Basal cell carcinoma (BCC)	4	109 [109]	Common findings: Dots, gray, blue or black (62%)
			Less common findings: Erosion/ulceration (46%); Lines, radial, connected to a common base (43%); Blue-white veil (29%); Lines, reticular, hypopigmented, around brown clods (28%); Structureless zone, red-white (22%); Lines, radial, converging to a central dot or clod (19%); Clods, blue to brown, large, clustered (18%); Dots or clods, white, clustered or disseminated (17%); Structureless zone, brown or black (11%); Clods, brown, yellow, or orange (rarely black) (11%); Branched vessels (11%); Clods, brown-blue, small (10%); Lines, reticular and thick (perilesional) (9%); Clods, blue, large, clustered (8%); Dots, blue and clods, blue, small (8%); Clods, white, shiny (8%); Circles, concentric (7%); Lines, radial (always at periphery) (6%); Structureless zone, white, central (5%); Looped vessels (3%); Follicular plugs (2%); Serpentine vessels (2%); Dot, non-specified color (2%); Structureless zone, blue (2%); Structureless zone, white (0.9%); Dots, brown (0.9%); Lines, white, perpendicularly (0.9%)
Keratoacanthoma	1	3[0]	Common findings: -
			Less common findings: -
Seborrheic keratosis(SK)
Classic SK	2	30[0]	Common findings: -
			Less common findings: -
Dermatosis papulosa nigra	1	100 [100]	Common findings: Lines, curved and thick (59%)
			Less common findings: Clods, brown, yellow, or orange (rarely black) (27%); Dots or clods, white, clustered or disseminated (8%)
Squamous cell carcinoma in situ (Bowen’s disease)	4	11[11]	Common findings: Dots, gray, blue (in a peripheral clustered or linear arrangement) (64%)
			Less common findings: Dots, brown, gray, blue (36%); Clods, brown (36%)
			Structureless zone, grey-white (36%); Coiled vessels, clustered (27%); Erosions/ulcerations (18%); Lines, radial (always at periphery) (18%); Coiled vessels (peripheral) (9%); Lines, blue-grey (radial) (9%); Looped vessels (9%); Lines, white (9%); Vessels (9%); Structureless, brown, and blue-grey (9%); Coiled vessels (9%); Clods (9%); Structureless, gray-black (9%)
Squamous cell carcinoma (SCC)
Pigmented	1	3[3]	Common findings: -
			Less common findings: Circles, white (33%)
Non-pigmented	1	4[4]	Common findings: Circles, white (75%); Erosions, ulcerations (75%); Dots, vessels (50%)
			Less common findings: Linear, irregular (25%); Clods, white, shiny (25%)
Not specified	1	4[0]	Common findings: -
			Less common findings: -
Adnexal cutaneous neoplasms
Apocrine hidrocystoma	2	10[8]	Common findings: Structureless, gray (100%)
			Less common findings: Dots, brown (13%); Branched vessels (13%)
Dilated pore of Winer	1	2[2]	Common findings: Follicular plug (100%); Structureless zone, blue (100%)
			Less common findings: -
Eccrine hidrocystoma	1	6[6]	Common findings: Structureless area, brown (100%)
			Less common findings: -
Eccrine syringofibroadenoma	1	1[1]	Common findings: Clods, brown or skin colored, large and polygonal (100%); Structureless zone, gray, white, or yellow (100%); Dots, white (100%)
			Less common findings: -
Nevus comedonicus	1	1[1]	Common findings: Clods, brown, yellow, or orange (rarely black) (100%); Follicular plugs (100%)
			Less common findings: -
Nevus sebaceous	1	7[7]	Common findings: -
			Less common findings: Structureless, yellow-gray (43%); Structureless, yellow, yellow-white (43%); Clods, large (43%); Lines, curved and thick, in combination with clods (29%); Dots or clods, white, clustered or disseminated (14%); Lines, curved and thick (14%); Looped vessels (14%); Linear vessels (14%)
Nodular hidradenoma	1	1[1]	Common findings: Structureless, white-gray (100%); Erosions/ulcerations (100%); Dots, gray or blue (100%); Polymorphous vessels (100%)
			Less common findings: -
Pilomatrixoma	1	1[1]	Common findings: Structureless, brown/yellow (100%); Lines, reticular (100%)
			Less common findings: -
Poroma	1	4[4]	Common findings: Branched vessels (100); Structureless area, white (100%); Structureless, yellow/yellow-brown (50%); Linear vessels (50%); Looped vessels (50%); Polymorphous
			vessels (50%)
			Less common findings: Structureless zone, brown or blue-gray (25%)
Reactive eccrine syringofibroadenoma	1	2[2]	Common findings: Structureless, gray/gray-white (100%); Clods, large and polygonal (100%)
			Less common findings: -
Sebaceous adenoma	1	1[1]	Common findings: Structureless, yellow/yellow-brown (100%); Clods, small, round or oval (blue-grey) (100%); Dots, brown (100%); Linear vessels (100%)
			Less common findings: -
Sebaceous hyperplasia	2	28[26]	Common findings: Structureless yellow/yellow-brown (100%)
			Less common findings: Linear vessels, radial (46%); Dots, gray or blue (31%); Branched vessels (4%)
Trichoblastoma	1	1[1]	Common findings: Structureless, brown (100%) Dots or clods, white (100%); Structureless, white (100%)
			Less common findings: -
Trichoepithelioma (familial)	1	4[4]	Common findings: Structureless zone, brown + dots or clods, white, clustered or disseminated (100%); Dots, brown (100%); Linear vessels (75%); Structureless zone, white (50%); Branched vessels (50%)
			Less common findings: Linear vessels, radial (25%)
Trichoepithelioma (solitary)	1	6[6]	Common findings: Structureless, brown/white (100%); Dots or clods, white, clustered or disseminated (100%)
			Less common findings: Dots, brown (33%); Linear vessels (17%))
Vascular tumors
Angiofibroma
Facial	3	9[5]	Common findings: Dots, yellow/white (100%); Structureless, brown, red-brown (80%);
			Dots, brown (80%)
			Less common findings: -
Penile	1	4[0]	Common findings: -
			Less common findings: -
Angiokeratoma	1	1[1]	Common findings: Clods, red-purple (100%); Lines, white (100%)
			Less common findings: -
Cherry angioma	1	10[10]	Common findings: Clods, red or purple (100%)
			Less common findings: Lines, reticular (peripheral), brown (20%)
Infantile hemangioma	1	1[1]	Common findings: Clods, red or purple (100%); Lines, white (100%)
			Less common findings:
Lymphangioma circumscriptum	1	3[0]	Common findings: -
			Less common findings: -
Pyogenic granuloma	1	39[0]	Common findings: -
			Less common findings: -
Connective tissue tumors
Dermatofibroma	4	112[112]	Common findings: Lines, reticular (71%); Structureless zone, white (63%)
			Less common findings: Lines: peripheral (41%); Structureless zone, white: central (36%); Structureless zone, brown (32%); Vessels (27%); Structureless zone, white: multifocal (27%); Structureless zone, brown: central (24%); Vessels: curved (21%); Vessels: dots (21%); Clods, small, round or oval (16%); Lines, white, perpendicularly (16%); Lines: multifocal (16%); Lines: uniform (14%); Vessels: linear (12%); Erosions/ulcerations (5%); Lines, radial (5%); Structureless zone, brown: peripheral (5%); Lines, reticular and thin (peripheral) (5%); Structureless zone, brown (central) (3%); Structureless zone, brown: eccentric (3%); Clods, brown, yellow, orange (rarely black) (3%); Lines, reticular, hypopigmented, around brown clods (3%); Dots or clods, white, clustered or disseminated (2%); Lines, reticular and thick or reticular lines that vary in color (1%); Structureless zone, blue-white (central) (1%); Lines, reticular and thin (1%); Structureless zone, white (central) (1%)
Dermatofibrosarcoma protuberans	2	2[1]	Common findings: Lines, reticular and thick or reticular lines that vary in color (100%); Lines, white, perpendicularly (100%); Serpentine vessels (100%)
			Less common findings: -
Fibrokeratoma	1	5[0]	Common findings: -
			Less common findings: -
Neurofibroma	1	4[0]	Common findings: -
			Less common findings: -
Cystic neoplasms and others
Epidermal cyst	2	11[4]	Common findings: -
			Less common findings: Structureless, yellow (25%); Structureless, gray (25%); Structureless zone, brown (25%)
Milia	1	3[0]	Common findings: -
			Less common findings: -
Trichilemmal cyst	1	5[5]	Common findings: -
			Less common findings: Structureless, brown (40%); Structureless, white + branched vessels (20%); Structureless zone, white (central or uniform) +/− structureless zone, brown/ lines, brown, curved, parallel, thin (20%); Structureless zone, white (central) +/− lines, brown, curved, parallel, thin (20%); Dots, gray, blue or black (20%)
Steatocytoma multiplex	1	1[0]	Common findings: -
			Less common findings: -
Mycosis fungoides (MF)
Classic MF	1	4[0]	Common findings: -
			Less common findings: -
Hypopigmented MF	1	4[0]	Common findings: -
			Less common findings: -
Folliculotropic MF	1	1[0]	Common findings: -
			Less common findings: -
Verrucous MF	1	2[0]	Common findings: -
			Less common findings: -

^*Dermoscopic findings for which a standardized terminology was available; these are divided into common (prevalence ≥ 50%) and less common (prevalence < 50%)

^**Total prevalence is calculated only considering studies for which prevalence data of dermoscopic findings was available

NA: Not applicable; NS: Not specified; CR: Case report; CS: Case series; C-C: Case-control study

Dermoscopic setting (polarised vs non-polarised) was reported in 8/20 records (3 polarized; 3 non-polarized; 2 both), magnification in 7/20 records (6: x10 magnification; 1: x20 magnification), and dermoscopic-pathological correlation in 4/20 records. Supplemental Table summarizes all such data, along with analytical description of each of the study evaluated in the review (number of patients, type of study and level of evidence), dermoscopic features, skin type of the patient, and corresponding terminology according to the IDS dermoscopic criteria for cutaneous neoplasms validated for skin of color. Table 1 also shows the general prevalence (calculated from all data reported in the literature) of dermoscopic findings of included tumors for which a standardized terminology was available. Relevant findings for each neoplasia are reported as follows; for practical purpose, we have grouped them according to the cellular/tissue origin. Figures 2–6 show dermoscopic clues of such conditions.

Figure 2.

Examples of dermoscopic clues of melanocytic neoplasms/keratinocytic tumors in dark-skinned patients: Brown lines (parallel, thin) in the furrows in acral melanocytic nevus (A); Structureless blue and black areas in blue nevus (B); Structureless blue and black areas along with brown lines (parallel, thick) on the ridges in acrolentiginous melanoma (C); White, black and blue structureless areas along with ulceration/erosions in nodular basal cell carcinoma (D); Numerous radial lines connected to a common base (spoke wheel-like areas) (arrow) and a diffuse white structureless area in superficial basal cell carcinoma (E); Central hyperkeratosis and hemorrhagic areas over a diffuse white structureless area surrounded by a brown halo in keratoacanthoma (F); Multiple brown and black dots and clods in seborrheic kerato-sis (G); Multiple brown dots (white arrow) and few dotted vessels (black arrow) along with diffuse white-brown hyperkeratosis in Bowen’s disease (H); Linear, irregular vessels over a diffuse white structureless area in squamous cell carcinoma (I).

Figure 3.

Examples of dermoscopic clues of adnexal tumors in dark-skinned patients: Central black follicular plug surrounded by a blue structureless zone in dilated pore of Winer (A); Brown-blue structureless area in eccrine hidrocystoma (B); Multiple brown-black follicular plugs in nevus comedonicus (C); Yellow-brown and white structureless areas (in some point featuring lines, curved and thick – “cerebriform pattern”) along with white-yellow clods (arrows) in sebaceous nevus (D); White structureless area in nodular hidradenoma (E); Yellow-white structureless areas over a red-brown diffuse structureless area in pilomatrixoma (F).

Figure 4.

Examples of dermoscopic clues of adnexal tumors in dark-skinned patients: Erosions and dotted vessels surrounded by white halo in eccrine poroma (A); Dotted and looped vessels surrounded by white halo in eccrine poroma (B); Yellow structureless areas and linear vessels in sebaceous adenoma (C); Yellow clods and yellow-brown structureless area in sebaceous hyperplasia (D); White structureless areas in trichoblastoma (E); White structureless area along with a white clod in trichoepithelioma (F).

Figure 5.

Examples of dermoscopic clues of vascular tumors in dark-skinned patients: Brown structureless area with white dots in facial angiofibroma (A); Red-purple clods separated by white lines in angiokeratoma (B); Red clods with reticular white lines and peripheral brown reticular lines in cherry angioma (C); Red clods separated by brown lines in infantile hemangioma (D); Yellow and red-brown clods sepa-rated by white or brown lines in lymphangioma circumscriptum (E); Red structureless areas along with white structureless areas in pyogenic granuloma (F).

Figure 6.

Examples of dermoscopic clues of connective tissue tumors, cystic neoplasms and others in dark-skinned patients: Brown structure-less area with perpendicular white lines in dermatofibroma (A); White as well as brown structureless areas in dermatofibrosarcoma protu-berans (B); Brown structureless areas and white structureless areas and lines in fibrokeratoma (C); White structureless areas in neurofibroma (D); Blue-grey structureless area in epidermal cyst (E); White structureless areas/clods in milia (F); Yellow structureless area in sebaceous cyst (steatocytoma multiplex) (G); Brown thick reticular lines in patch-stage mycosis fungoides (H) (adapted from Dermoscopy in General Dermatology for Skin of Color, Errichetti E, Lallas A, eds. CRC Press 2021); White structureless area with a few brown lines in hypopigmented mycosis fungoides (I).

Melanocytic Neoplasms

Melanocytic Nevi

Dermoscopy of melanocytic nevi has been reported to vary based on the histological subtype, localization, and skin tone (in the spectrum of Fitzpatrick’s phototypes IV–VI) [9–13]. According to a case-control study by Lallas et at involving 300 patients (excluding facial and acral lesions), the main morphological patterns of common acquired melanocytic nevi included reticular, globular and structureless, whereas the most frequent pigment arrangements turned out to be uniform and “central hyperpigmentation” [9]. Such findings are consistent with data coming from other studies (a case-control study [10] and a case-series [11]) including a total of 455 lesions. Of note, structureless pattern and black, blue and grey color were observed more common in Fitzpatrick skin type VI patients, while skin type V individuals mainly showed dark brown reticular pattern [9].

Moving to special sites, Madankumar et al found parallel furrow pattern to be the most common presentation of acral melanocytic nevi in a case-series on 369 lesions [12]. On the other hand, pigmented pseudonetwork was reported as the pattern of facial melanocytic nevi in a case-series by De Giorgi et al, yet no specification on the number of included lesions was mentioned [11]. The same study reported blue homogeneous pattern as a constant finding in four instances of blue nevi [11].

Melanoma

All the data retrieved from the literature concerned acral lentiginous melanoma (ALM). Most of the information comes from the study (case-series) by Manci et al involving a total of eight dermoscopic instances, that constantly showed structureless areas with multiple shades of brown, blue, black, and pink colors [13].

Other common findings (more than two-thirds of cases) included parallel ridge pattern, diffuse plantar lentigines, and parallel ridge pattern of surrounding skin [13]. Fibrillar pattern of surrounding skin, peripheral hypopigmentation, ulceration, and atypical fibrillar pattern were less frequent features [13]. No specification about melanoma thickness was reported for all the above-mentioned instances [13].

Finally, irregular streaks, irregular globules, and blue-whitish veil were detected in a case of invasive ALM (Breslow’s thickness: 1.2 mm) by De Giorgi et al [11].

Keratinocytic Tumors

Basal Cell Carcinoma

The main study on dermoscopy of basal cell carcinoma (BCC) is a retrospective observational analysis (case-series) by Behera et al on 60 lesions (32 nodular, 27 superficial and 1 infiltrative subtype) [14]. The most common features of nodular BCC were ulceration (84.3%) and blue-white veil (81.2%), followed by brown to blue-gray ovoid nests (40.6%), whereas maple leaf-like area (92.5%), red-white homogenous area (66.6%), multiple small erosions (59.2%), short fine telangiectasia (59.2%), spoke wheel-like areas (55.5%) turned out to be the main findings of superficial BCC [14]. Notably, the prevalence of all the aforementioned features was found to be statistically significant for the corresponding subtype (nodular vs superficial) [14]; arborizing vessels were also indicative of nodular BCC, though they were seen only in 37.5% of cases [14].

Besides the detection of shiny white blotches/strands and pigmented structures (mainly leaf-like areas, blue-gray ovoid nests, and multiple blue-gray dots/globules) in half lesions (9/18), Manci et al also commonly observed loss of normal background pigmentation/network (72.2%), milky red area (66.7%), and accentuated normal background pigmentation/ network surrounding the lesion (55.6%) [13]. Importantly, no specification about the histological subtype was provided in this dermosopic analysis [13].

Additional dermoscopic findings retrieved from the two above-mentioned studies [13,14] and other analyses (one case-series on 30 patients [15] and one single case-report [16]) included negative pigment network, concentric structures, brown to blue to blue-gray aggregates, coarse peppering, peripheral striations, follicular plugging, peri-follicular white rings, brown to black blotch, adherent fabric fibers, milia-like cyst, comedo-like opening, in-focus dots, central or peripheral hypopigmentation, atypical vessel running across the lesion, hemorrhages, hairpin vessels, linear-irregular vessels, chrysalis-like structures, multiple aggregated yellow/white, and scales/crusts.

Keratoacanthoma

The only available data on keratoacanthoma comes from a case-series including three lesions that displayed keratin-related structures, including white scales/crusts, yellow/orange crusts and central white areas, along with radially arranged hairpin vessels, linear-irregular vessels, hemorrhages, and brown areas [15]. Of note, no specific data on their prevalence of such findings was provided [15].

Seborrheic Keratosis

Dermoscopy of seborrheic keratosis has been investigated in two descriptive studies (case-series) involving a total of 30 instances (15 for each analysis) [11,15]. Reported findings included “moth eaten” borders, comedo-like openings, milia-like cysts, “fat fingers”, cerebriform pattern, “finger print” pattern, surface white scaling, and “parchment-like” thick crust [11,15]. Of note, prevalence of each of the aforementioned findings was not specified; vessels were absent in all cases [11,15].

Moving to dermatosis papulosa nigra (a variant of seborrheic keratosis commonly seen in dark phototypes), an observational study (case-series) on 100 patients by Bhat et al found cerebriform pattern to be the main feature (59% of cases), followed by comedo-like openings (27% of cases), while milia-like cysts were observed only in 8% of instances [17].

Squamous Cell Carcinoma in Situ (Bowen’s Disease)

The main study on dermoscopy of Bowen’s disease is a case-series including eight lesions (seven pigmented and one non-pigmented) by Behera et al, who found brown to blue-gray dots/globules (in a peripheral clustered or linear arrangement) to be the main finding (7 lesions), followed by scales (6 lesions) and light to dark brown keratotic structureless areas (5 lesions) [18]. Such structures were also detected in other three single reports [15,19,20].

Additional findings included clustered (and less commonly peripheral) glomerular vessels, brown to blue-gray peppering (fine and coarse), blue-grey radial lines, ulcerations/ erosions, blood spots/crusts, hairpin vessels, ring-like pattern, ill-defined gray outer border, well-defined thin brown outer border, interconnecting white lines, and grey-white/red-white areas [18].

Squamous Cell Carcinoma

Most of data on dermoscopic findings of squamous cell carcinoma (SCC) comes from a case-series by Manci et al on seven instances, including three pigmented and four non-pigmented lesions [13]. In detail, adherent scales with pigment and peripheral hypopigmentation with loss of pigmented network in surrounding skin were constant findings of pigmented SCC, while non-pigmented mainly showed adherent white scale (100%) along with white circles and ulceration (both 75%) [13].

Further features for pigmented SCC included milky-red areas and white circles, while dotted vessels, serpentine vessels, shiny white strands, peripheral hypopigmentation with loss of pigmented network seen in surrounding skin, and peripheral islands of hyperpigmentation turned out to be additional findings of non-pigmented SCC [13].

In a descriptive analysis (case-series) including four SCCs, Ankad et al observed white and red structureless areas, along with ulcerations, blood spots and polymorphic vascular pattern (i.e., dotted, linear-irregular, arborizing, atypical, unspecific and hairpin vessels); no specification about subtype (pigmented vs non-pigmented) and prevalence of dermoscopic findings was available [15].

Adnexal Cutaneous Neoplasms

Apocrine Hidrocystoma

A total of 10 lesions have been assessed by two case-series [15, 21]. Grey homogenous area was found to be a constant finding by Behera et al in a series of 8 lesions, whereas peripheral erythema, light brown peppering and arborising vessels were observed less commonly [21].

On the other hand, Ankad et al by analyzing two lesions reported yellowish-brown homogeneous area covering whole lesion, linear irregular vessels running across the lesion, and white globules, yet specific data on their prevalence were not specified [15].

Dilated Pore of Winer

Two instances of dilated pore of Winer have been retrieved, with central black keratotic plug and bluish white homogenous areas being described in both the cases [21].

Eccrine Hidrocystoma

Data on dermoscopy of eccrine hidrocystoma comes from the observational study (case-series) by Behera et al, who assessed six lesions from a single patient and constantly found a skin-colored homogenous area [21].

Nevus Sebaceous

Seven instances of nevus sebaceous (without secondary tumors) were evaluated by dermoscopy, with the main features being papillary to knob-like pattern with a yellow to grey background and yellow to yellow-white homogenous area/ovoid nest (both observed in three lesions) [21]. Additional findings included linear irregular crypts, cerebriform pattern, milia-like cysts, hairpin vessels, and linear vessels [21].

Poroma

Four cases reporting dermoscopic findings of poroma have been retrieved from the literature. In detail, diffuse white structureless area and branched vessels with a round ending were seen in all lesions, while further features included focal yellow to yellow-brown structureless area, linear or hairpin vessels, polymorphous vascular pattern, and brown to blue-grey blotch [21].

Sebaceous Hyperplasia

The main dermoscopic study on sebaceous hyperplasia is an observational analysis (case-series) including 26 lesions from six patients [21]. Yellow/yellow-brown homogenous area and single to multiple puncta were seen in all instances, whereas fine brown to blue-grey peppering, crown vessels, linear-branching vessels were additional findings [21]. Besides yellow globules and crown vessels, pale white septae and patulous follicles were also found in another series of two instances [15].

Syringoma

Most of data on dermoscopy of syringomas comes from the analysis (case-series) by Behera et al including 119 lesions (1 chondroid syringoma, 24 non-pigmented syringomas, 64 pigmented syringomas, 10 milium-like syringomas, and 20 eruptive syringomas) from 16 patients [21]. The main finding shared by all the subtypes (apart from chondroid syringoma) was the presence of milia-like cysts [21]. Other common general features included yellow/yellow-brown homogeneous area and pigment network [21]. Such findings are in line whit what observed by Ankad et al in five instances of syringoma [15].

Trichoepithelioma

One study assessing dermoscopy of ten trichoepitheliomas (six solitary and four familial) from nine patients is available [21]. Skin-colored to white homogenous area with milia-like cysts was a constant finding in both solitary and familial lesions; additionally, fine brown peppering was also detected in all familial instances [21]. Further features included focal white homogenous area and linear, arborizing and crown vessels [21].

Other Adnexal Cutaneous Neoplasms

This group includes adnexal cutaneous tumors retrieved in the review analysis whose dermoscopic data is based on single reports/small series, i.e., eccrine syringofibroadenoma, nevus comedonicus, nodular hidradenoma, pilomatrixoma, reactive eccrine syringofibroadenoma, sebaceous adenoma, and trichoblastoma [21]. Reported dermoscopic findings are showed in Table 1/Supplemental Table.

Vascular Tumors

Angiofibroma

A total of nine instances from three analyses (two case series and a single report) were assessed by dermoscopy [15,21,22]. The most common feature reported by all the studies included white/yellow-white dots [15,21,22]; other frequent findings were, brown/reddish-brown background, unfocused vessels, and brown dots [22].

Angiokeratoma

Only one instance of angiokeratoma reporting dermoscopic findings is available, with description of pink to purplish lagoons, whitish ground glass film, and thick septa separating each lacuna [15].

Cherry Angioma

Knowledge on dermoscopy of cherry angioma comes from the descriptive analysis (case-series) by Ankad et al including 10 instances [15]. In all cases, red to purplish lagoons were seen, while milky-white veil was prominent in older lesions and a rim pigment network was noted in two lesions [15].

Infantile Hemangioma

Only one case of infantile hemangioma has been investigated from a dermoscopic point of view, with red lacunae and white septa being reported [23].

Lymphangioma Circumscriptum

Information on dermoscopy of lymphangioma circumscriptum comes from a series of three cases, that showed pale yellow/pale pink lacunae (with some of them filled with purplish globules) and white septa; no prevalence data was provided [15].

Pyogenic Granuloma

A total of 39 lesions were analyzed by dermoscopy in the only available study (case-series). In this analysis, reddish homogeneous areas, white collarette, white rail line and vascular structures were observed, yet specific data on their prevalence were not provided [15].

Connective Tissue Tumors

Dermatofibroma

The main study on dermoscopy of dermatofibroma is the analysis (case-series) by Kelati et al including a total of 100 lesions from 95 patients (mainly phototype IV) [24]. According to this study, the most common dermoscopic features (more than two-thirds of cases) included pigmented network (mainly located at the periphery) and white patches (“central scar-like” or “eccentric multiple”) [24]. Moreover, central homogeneous pigmentation was also frequently reported (36% of cases) [24], in line with a small case-series by Giddens et al [25]. Many other additional findings have been described and are displayed in the Supplemental Table [11, 15, 24, 25].

Dermatofibrosarcoma Protuberans

Two case-reports described dermoscopy of dermatofibrosarcoma protuberans [26,27]. In detail, both instances showed atypical/interrupted network [26,27]; additionally, hyper/hypo-pigmented structureless areas, shiny white streaks and unfocused linear-irregular vessels were noted in the first case [26] and a pinkish background in the second case [27].

Fibrokeratoma

The only analysis on dermoscopy of fibrokeratoma included five cases, with the following findings being reported (no prevalence data was available): homogeneous brownish-white and rosy-white area, white structureless areas (tree branches-like arrangement), and dotted/linear vessels [15].

Neurofibroma

Dermoscopic findings based on the analysis of four instances included in a study by Ankad et al were pink-red homogeneous areas, peripheral pigment network and fissures, and scar-like white areas with star burst appearance, yet they prevalence was not specified [15].

Cystic Neoplasms and Others

Epidermal Cyst, Milia and Trichilemmal Cyst

Two case-series investigated dermoscopy of such lesions for a total of three milia, 11 epidermal cysts, and five trichilemmal cysts [15,21]. In detail, white to yellow homogeneous area was the main finding for all of them; linear (milia) or branching (epidermal and trichilemmal cysts) vessels were also reported [15,21]. Additionally, brownish peripheral rim was found in milia and trichilemmal cysts, while central pore/punctum was described in epidermal cyst [15,21].

Steatocytoma Multiplex

A single description of this entity was retrieved, with yellow homogeneous area covering the entire lesion, linear vessels, and peripheral brown rim being reported [15].

Mycosis Fungoides

Only one observational study (case-series) on dermoscopy of mycosis fungoides (MF) was available. In this analysis, Nakamura et al assessed 33 images from 11 patients (four classic MF, four hypopigmented MF, one folliculotropic MF, and two verrucous MF), yet no data on prevalence of dermoscopic findings was provided [28].

Classic MF was reported to show striking pigmentary change, thick black lines, white rosettes, and geometric white lines, while hypopigmented MF was characterized by the loss of natural pigment network [28]. On the other hand, follicular plugging along with hyperpigmented to violaceous perifollicular halos and yellow-gray amorphous structures coupled with yellow-gray ridges/comedo-like openings within hyperkeratotic areas were observed in folliculotropic and verrucous MF, respectively [28].

Conclusions

This review emphasizes that many skin neoplasias have been investigated from a dermoscopic point of view in dark-skinned patients with description of potentially useful diagnostic features, though most of available data comes from inhomogeneous/unstructured studies either including small samples (especially case reports/series) or lacking comparative analyses, thereby results have to be confirmed through studies with a more robust statistical design. Moreover, available information for some tumors concerns only some tones of “dark skin” spectrum (especially phototype IV). Nevertheless, the possible correspondence between histopathological changes of cutaneous tumors and dermoscopic findings even in skin of color makes oncological dermoscopy a potential useful aid in dark phototypes too [8]. Future comprehensive studies using a homogeneous/standardized approach will help in this regard.

Supplementary Material

Supplemental Table S1.

Summary of dermoscopic features of skin neoplasms in skin of color

Tumor	Studies (First author, year and corresponding reference)	Dermoscopic findings (prevalence in percentage)	Corresponding terminology (descriptive) based on International Dermoscopy Society criteria for tumors validated for skin of color	Histological correlates	Dermoscopic setting (polarization or not/magnification)	Cases (n)	Type of study	Level of evidence	Skin phototype
Melanocytic neoplasms
Melanocytic nevi Acral melanocytic nevi	Madankumar R, et al. 201612	• Parallel furrow (43%)	• Lines, parallel, thin, in the furrows	• NS	NS/NS	396 lesions	CS	V	IV-VI
		• Lattice-like (13%)	• Lines, parallel, thin, in the furrows and crossing the ridges	• NS
		• Fibrillar (7%)	• Lines, parallel, short, crossing ridges	• NS
		• Homogenous (10%)	• Structureless	• NS
		• Parallel ridge (1%)	• Lines, parallel, thick, on the ridges	• NS
Melanocytic nevi Blue nevus	De Giorgi V, et al. 200611	• Homogeneous bluish pigmentation in the absence of other dermoscopic features (100.0%)	• Structureless, blue	• NS	NS/NS	4	CS	V	NS (“Black people”)
Melanocytic nevi Melanocytic nevi (not considering specific sites or histological types)	Lallas A, et al. 20149	Morphological pattern			NS/NS	300	C-C	IV	V,VI
		• Globular (V 15.4%; VI 12.5%)	• Clods, small, round or oval	• NS
		• Reticular (V 44.7%; VI 33.3%)	• Lines, reticular	• NS
		• Structureless (V 18.9%; VI 40.3%),	• Structureless	• NS
		• Globular + reticular (V 3.5%; VI 13.9%)	• Clods, small, round or oval + lines, reticular	• NS
		• Globular + structureless (V 4.4%; VI 0.0%)	• Clods, small, round or oval + structureless	• NS
		• Reticular + structureless (V 13.2%; VI 0.0%)	• Lines, reticular + structureless	• NS
		Pigment distribution	• NA	• NS
		• Uniform (V 61.4%; VI 84.7%)	• NA	• NS
		• Central hyperpigmentation (V 28.9%; VI 4.2%),
		• Central hypopigmentation (V 1.8%; VI 0.0%),	• NA	• NS
		• Peripheral hyperpigmentation (V0.9%; VI 2.8%),	• NA	• NS
		• Patchy (V 6.1%; VI 6.9%)	• NA	• NS
		• Unspecific (V 0.9%; VI 1.4%)	• NA	• NS
		Color
		• White (V 0.0%; VI 1.4%)	• White	• NS
		• Red (V 0.0%; VI 1.4%)	• Red	• NS
		• Light brown (V 7.9%; VI 28.0%)	• Brown	• NS
		• Dark brown (V 89%; VI 55.5%)	• Brown	• NS
		• Blue (V 7.0%; VI 22.2%)	• Blue	• NS
		• Grey (V 9.6%; VI 23.6%)	• Grey	• NS
		• Black (V 22.4%; VI 66.7%)	• Black	• NS
	Tuma B et al. 201510	Morphological pattern			NS/NS	376	C-C	IV	V,VI
		• Reticular (66.2%)	• Lines, reticular	• NS
		• Reticular/structureless (14.1%)	• Lines, reticular/structureless	• NS
		• Structureless (8.8%)	• Structureless	• NS
		• Globular structureless (2.7%)	• Clods, small, round or oval/structureless	• NS
		• Globular-reticular (2.7%)	• Clods, small, round or oval/lines, reticular	• NS
		• Reticular-globular (2.4%)	• Lines reticular/clods, small, round or oval	• NS
		• Globular (2.1%)	• Clods, small, round or oval	• NS
		• Starburst (1.1%)	• Pseudopods, circumferential or lines, radial, circumferential	• NS
		Pigment distribution
		• Uniform (64.4%)	• NA	• NS
		• Central hyperpigmentation (18.9%),	• NA	• NS
		• Multifocal hypo/hyperpigmentation (10.6%)	• NA	• NS
		• Eccentric hyperpigmentation (5.9%),	• NA	• NS
		• Central hypopigmentation (0.3%)	• NA	• NS
		Color
		• Dark brown (41.8%)	• Brown	• NS
		• Light brown (38.5%)	• Brown	• NS
		• Blue-gray (14.6%)	• Blue-gray	• NS
		• Black (4.7%)	• Black	• NS
		• Red (0.3%)	• Red	• NS
	De Giorgi V, et al. 200611	• Regular pigmented network that fades to the periphery (100%)	• Lines, reticular	• NS	NS/NS	79	CS	V	NS (“Black people”)
		• Globules (NS)	• Clods, small, round or oval	• NS
		• Pigmented pseudonetwork (facial lesions) (NS)	• Structureless, brown, interrupted by follicular openings	• NS
Melanoma (acrolentiginous, excluding nails)	Manci R, et al. 202213	• Brown, blue, black, and pink structureless areas (100.0%)	• Structureless, brown, blue, black	• NS	NS/NS	8	CS	V	NS (“Subjects who self-identified as black”)
		• Parallel ridge pattern (75.0%)	• Lines, parallel, thick, on the ridges	• NS
		• Ulceration (25.0%)	• Erosion/ulceration	• NS
		• Atypical fibrillar pattern (25.0%)	• NA	• NS
		• Parallel ridge pattern of surrounding skin (100.0%)	• Lines, parallel, thick, on the ridges	• NS
		• Fibrillar pattern of surrounding skin (57.1%)	• Lines, parallel, short, crossing ridges	• NS
		• Peripheral hypopigmentation (57.1%)	• NA	• NS
		• Diffuse plantar lentigines (71.4%)	• NA	• NS
		• Hypopigmented “halo” (57.1%)	• NA	• NS
	De Giorgi V, et al. 200611	• Blue-whitish veil (100.0%)	• Structureless zone, blue	• NS	NS/NS	1	CR	V	NS (“Black people”)
		• Irregular globules (100.0%)	• Irregular clods, small	• NS
		• Peripheral streaks (100.0%)	• Lines, radial (always at periphery)	• NS
Keratinocytic tumors
Basal cell carcinoma (BCC)	Behera B, et al. 202114	Classic BCC-associated features			Nonpolarized/x10	60 lesions from 35patients	CS	V	IV, V
		• Ulceration (48.4%)	• Erosion/ulceration	• NS
		• Maple leaf-like area (61.7%)	• Lines, radial, connected to a common base	• Basaloid lobules near the dermo-epidermal junction
		• Brown to blue-gray ovoid nest (33.4%)	• Clods, blue to brown, large, clustered	• Large basaloid lobules
		• Brown to blue-gray globule (18.4%)	• Clods, brown-blue, small	• NS
		• Arborizing vessels (20.0%)	• Branched vessels	• NS
		• Spoke wheel area (26.7%)	• Lines, radial, converging to a central dot or clod	• NS
		Non classic BCC-associated features
		• Multiple small erosions (31.7%)	• Erosions/ulcerations	• NS
		• Short fine telangiectasias (46.7%)	• NA	• NS
		• Concentric structure (13.3%)	• Circles, concentric	• Small tumor nests with darkly pigmented centers arising from (and connected to)the epidermis
		• In-focus dot (3.3%)	• Dot, non-specified color	• Free pigment or melanophages/small aggregates of pigmented neoplastic tumor cells
		• Red-white homogenous area (40.0%)	• Structureless zone, red-white	• NS
		Nonspecific features
		• Blue-white veil (53.4%)	• Structureless zone, blue	• Heavily pigmented dermal melanocytes and/or melanophages or melanin combined with compact orthokeratosis
		• Brown to blue-gray aggregate/ coarse peppering (43.4%)	• Dots, gray, blue or black	• NS
		• Brown to blue-gray fine peppering (68.4%)	• Dots, gray, blue or black	• NS
		• Brown to black blotch (20.0%)	• Structureless zone, brown or black	• NS
		• Milia-like cysts (31.7%)	• Dots or clods, white, clustered or disseminated	• NS
		• Comedo-like openings (20.0%)	• Clods, brown, yellow, or orange (rarely black)	• NS
		• Scale (23.3%)	• NA	• NS
		• Peripheral striations (10.0%)	• Lines, radial (always at periphery)	• NS
		• Follicular plugging (3.3%)	• Follicular plugs	• NS
		• Peri-follicular white ring (15%)	• NA	• NS
		• Keratin (16.7%)	• NA	• NS
		Other vascular structures
		• Hemorrhage 35 (58.3%)	• NA	• NS
		• Hairpin vessels 3 (5.0%)	• Looped vessels	• NS
		• Linear irregular vessels 2 (3.3%)	• Serpentine vessels	• NS
	Ankad BS, et al. 201715	All cases
		• Negative pigment network (100%)	• Lines, reticular, hypopigmented, around brown clods	• NS	Polarized-nonpolarized/NS	30	CS	V	NS (“Brown skin”)
		Pigmented BCC
		• Blue gray ovoid nests (NS)	• Clods, blue, large, clustered	• NS
		• Maple leaf-like structures (NS)	• Lines, radial, connected to a common base	• NS
		• Whitish blue veil (NS)	• Structureless zone, blue	• NS
		• Ulcerations (NS)	• Ulceration	• NS
		• Spoke wheel patterns (NS)	• Lines, radial, converging to a central dot or clod	• NS
		Nodular BCC
		• Arborizing vessels (NS)	• Branched vessels	• NS
		• Blue gray globules (NS)	• Clods, blue, small	• NS
		• White areas (NS)	• Structureless zone, white	• NS
		• Atypical vessel running across the lesion (3.3%)	• NA	• NS
	Manci R, et al. 202213	• Loss of normal background pigmentation and network (72.2%)	• NA	• NS	NS/NS	18 lesions from 5 patients	CS	V	NS (“Subjects who self-identified as black”)
		• Milky red area (66.7%)	• NA	• NS
		• Accentuated normal background pigmentation network surrounding the lesion (55.6%)	• Lines, reticular and thick (perilesional)	• NS
		• Leaf-like areas (50.0%)	• Lines, radial, connected to a common base	• NS
		• Blue-gray ovoid nests (50.0%)	• Clods, blue, large, clustered	• NS
		• Multiple blue-gray dots and globules (50.0%)	• Dots, blue and clods, blue, small	• NS
		• Shiny white blotches and strands (50.0%)	• Clods, white, shiny	• NS
		• Central hypopigmentation (33.3%)	• Structureless zone, white, central	• NS
		• Spoke-wheel like structures (22.2%)	• Lines, radial, converging to a central dot or clod	• NS
		• Scale and/or crust (11.1%)	• NA	• NS
		• Multiple aggregated yellow-white (MAY) globules (5.6%)	• NA	• NS
		• Milky white areas (5.6%)	• Structureless zone, white	• NS
		• Ulceration (5.6%)	• Erosions/ulcerations	• NS
		• Peripheral hypopigmentation (5.6%)	• NA	• NS
	Kinnera B, et al. 202016	Pigmented BCC
		• Absence of pigmentary network (100.0%)	• NA	• NS	Polarized/x10	1	CR	V	NS (“Brown skin”)
		• Peripheral maple leaf–like structures (100.0%)	• Lines, radial, connected to a common base	• NS
		• Blue-gray structureless areas (100.0%)	• Structureless zone, blue	• NS
		• Multiple spoke wheel-like structures (100.0%)	• Lines, radial, converging to a central dot or clod	• NS
• Blue-white veil (100.0%)		• Structureless zone, blue	• NS
• Adherent fabric fibers (100.0%)		• NA	• NS
• Brown dots (100.0%)		• Dots, brown	• NS
• Erosions (100.0%)		• Erosions/ulcerations	• NS
• Adherent and shiny white chrysalis like structures (100.0%)		• Lines, white, perpendicularly	• NS
Keratoacanthoma	Ankad BS, et al. 201715	• Crust (orange, white, yellow) (NS)	• NA	• NS	Polarized-nonpolarized/NS	3	CS	V	NS (“Brown skin”)
		• Central white areas (NS)	• Structureless, white (central)	• NS
		• Linear irregular vessels (NS)	• Serpentine vessels	• NS
		• Radially arranged hairpin vessels (NS)	• Looped vessels, radial	• NS
		• Blood spots (NS)	• NA	• NS
		• Brown areas (NS)	• Structureless zone, brown	• NS
Seborrheic keratosis (SK) Classic SK	Ankad BS, et al. 201715	• Moth-eaten borders (NS)	• Sharply demarcated, scalloped border	• NS	Polarized-nonpolarized/NS	15	CS	V	NS (“Brown skin”)
		• Comedo-like openings (NS)	• Clods, brown, yellow, or orange (rarely black)	• NS
		• Milia-like cysts (NS)	• Dots or clods, white, clustered or disseminated	• NS
		• Fat fingers (NS)	• Lines, curved and thick	• NS
		• Cerebriform pattern (NS)	• Lines, curved and thick	• NS
		• Fingerprint patterns (NS)	• Lines, brown, curved, parallel, thin	• NS
		• “Parchment-like” thick crust (NS)	• NA	• NS
		• Surface white scaling (NS)	• NA	• NS
		• Hairpin vessels not evident in all the lesions (NS)	• Looped vessels	• NS
	De Giorgi V, et al. 200611	• Milia-like cysts (NS)	• Dots or clods, white, clustered or disseminated	• NS	NS/NS	15	CS	V	NS (“Black people”)
		• Pseudofollicular openings (NS)	• NA	• NS
		• Absence of pigmented network (NS)	• NA	• NS
Seborrheic keratosis Dermatosis papulosa nigra	Bhat RM, et al. 201717	• Fissures and ridges (59.0%)	• Lines, curved and thick	• NS	NS/NS	100	CS	V	NS(Literature from India)
		• Comedo-like openings (27.0%)	• Clods, brown, yellow, or orange (rarely black)	• NS
		• Milia-like cysts (8.0%)	• Dots or clods, white, clustered or disseminated	• NS
Squamous cell carcinoma in situ (Bowen’s disease)	Behera B, et al. 202118	• Blue-gray dots/globules (in a peripheral clustered or linear arrangement) (87.5%)	• Dots, gray, blue (in a peripheral clustered or linear arrangement)	• NS	Nonpolarized/x10	8 lesions (7 pigmented and 1 non-pigmented) from 5 patients	CS	V	IV, V
		• Scales (75.0%)	• NA	• NS
		• Light to dark brown keratotic structureless areas (62.5%)	• NA	• NS
		• Brown to blue-gray peppering (fine and coarse) (50.0%)	• Dots, brown, gray, blue	• NS
		• Ill-defined gray outer border (50.0%)	• NA	• NS
		• Grey-white areas (50.0%)	• Structureless zone, grey-white	• NS
		• Clustered glomerular vessels (37.5%)	• Coiled vessels, clustered	• NS
		• Blood spots/crusts (37.5%)	• NA	• NS
		• Ulcerations/erosions (25.0%)	• Erosions/ulcerations	• NS
		• Well-defined thin brown outer border (25.0%)	• NA	• NS
		• Red-white areas (25.0%)	• NA	• NS
		• Peripheral glomerular vessels (12.5%)	• Coiled vessels (peripheral)	• NS
		• Blue-grey radial lines (12.5%)	• Lines, blue-grey (radial)	• NS
		• Hairpin vessels (12.5%)	• Looped vessels	• NS
		• Ring-like pattern (12.5%)	• NA	• NS
		• Interconnecting white lines (12.5%)	• Lines, white	• NS
	Ankad BS, et al. 201715	• Structureless brown globules (100.0%)	• Clods, brown	• NS	Polarized-nonpolarized/NS	1	CR	V	NS (“Brown skin”)
		• Hypopigmented brown regular globules (100.0%)	• Clods, brown	• NS
		• Regression-like areas (100.0%)	• NA	• NS
		• Scaling (100.0%)	• NA	• NS
		• Vessels (100.0%)	• Vessels	• NS
		• Blood spots (100.0%)	• NA	• NS
		• Erythema (100.0%)	• NA	• NS
	Gutiérrez-Mendoza D, et al. 201019	• Central structureless brown and blue-gray pigmentation (100.0%)	• Structureless, brown, and blue-gray	• NS	NS/x10	1	CR	V	IV
		• Irregular peripheral pigmented streaks (100.0%)	• Lines, radial (always at periphery)	• NS
		• Linear brown regular globules (100.0%)	• Clods, brown	• NS
		• Linear and clustered light brown regular globules on the lower two thirds (100.0%)	• Clods, brown	• NS
		• Patches of clustered glomerular vessels (100.0%)	• Coiled vessels	• NS
		• Structureless hypopigmented central area (100.0%)	• NA	• NS
	Vivan MM, et al. 201720	• Amorphous light brown area adjacent to a dark brown area (100.0%)	• NA	• NS	NS/NS	1	CR	V	IV
		• Irregularly distributed globules (100.0%)	• Clods	• NS
		• Streaks (100.0%)	• Lines, radial (always at periphery)	• NS
		• Grayish-black portions (100.0%)	• Structureless, gray-black	• NS
Squamous cell carcinoma (SCC)	Manci R, et al. 202213	Pigmented SCC (N=3)			NS/NS	7	CS	V	NS (“Subjects who self-identified as black”)
		• Adherent scales with pigment (100.0%)	• NA	• NS
		• Peripheral hypopigmentation (100.0%)	• NA	• NS
		• Loss of pigmented network seen in surrounding skin (100.0%)	• NA	• NS
		• White circles (33.3%)	• Circles, white	• NS
		• Milky-red areas (33.3%)	• NA	• NS
		Non-pigmented SCC (N=4)
		• Adherent white scale (100.0%)	• NA	• NS
		• White circles (75.0%)	• Circles, white	• NS
		• Ulceration (75.00)	• Erosions, ulcerations	• NS
		• Peripheral hypopigmentation, loss of pigmented network seen in surrounding skin (50.0%)	• NA	• NS
		• Dotted vessels (50.0%)	• Dots, vessels	• NS
		• Serpentine vessels (25.0%)	• Linear, irregular	• NS
		• Shiny white strands (25.0%)	• Clods, white, shiny	• NS
		• Peripheral islands of hyperpigmentation (25.0%)	• NA	• NS
	Ankad BS, et al. 201715	• White structureless areas (NS)	• Structureless, white	• NS	Polarized-nonpolarized/NS	4	CS	V	NS (“Brown
		• Prominent atypical, dotted and irregular vessels (NS)	• Dots, vessels	• NS
		• White circles or pearls (NS)	• Circles, white	• NS
		• Color patterns: white structureless areas, red homogenous areas (NS)	• Structureless, white	• NS
		• Vessels: dotted, irregular, atypical/looped/unspecific (NS)	• Vessels: dots, serpentine, looped	• NS
		• Blood spots (NS)	• NA	• NS
		• Ulceration (NS)	• Erosions, ulcerations	• NS
Adnexal cutaneous neoplasms
Apocrine hidrocystoma	Behera B, et al. 202121	• Grey homogenous area (100.0%)	• Structureless, gray	• NS	Nonpolarized/x10	8 lesions from 1 patient	CS	V	IV, V
		• Peripheral erythema (25.0%)	• NA	• NS
		• Light brown peppering (12.5%)	• Dots, brown	• NS
		• Arborizing vessels (12.5%)	• Branched vessels	• NS
	Ankad BS, et al. 201715	• Yellowish-brown homogeneous area covering whole lesion (NS)	• Structureless, yellow-brown	• NS	Polarized-nonpolarized/NS	2	CS	V	NS (“Brown skin”)
		• Linear irregular vessels running across the lesion (NS)	• Serpentine vessels	• NS
		• White globules (NS)	• Clods, white	• NS
Dilated pore of Winer	Behera B, et al. 202121	• Central black keratotic plug (100.0%)	• Follicular plug	• NS	Nonpolarized/x10	2	CS	V	IV, V
		• Bluish white homogenous area (100.0%)	• Structureless zone, blue	• NS
Eccrine hidrocystoma	Behera B, et al. 202121	• Skin-colored homogenous area (100.0%)	• Structureless area, brown	• NS	Nonpolarized/x10	6 lesions from 1 patient	CS	V	IV, V
Eccrine syringofibroadenoma	Behera B, et al. 202121	• Cobblestone pattern (100.0%)	• Clods, brown or skin colored, large and polygonal	• NS	Nonpolarized/x10	1	CR	V	IV, V
		• Greyish-white to yellow structureless area (100.0%)	• Structureless zone, gray, white, or yellow	• NS
		• Interlacing white lines forming a network-like pattern (100.0%)	• NA	• NS
		• Prominent eccrine duct openings (100.0%)	• Dots, white	• NS
Nevus comedonicus	Behera B, et al. 202121	• Multiple comedo-like openings (100.0%)	• Clods, brown, yellow, or orange (rarely black)	• NS	Nonpolarized/x10	1	CR	V	IV, V
		• Brown keratotic plugs (100.0%)	• Follicular plugs	• NS
Nevus sebaceous	Behera B, et al. 202121	• Papillary to knob-like pattern (42.8%)	• NA	• Acanthotic and papillomatous epidermis	Nonpolarized/x10	7	CS	V	IV, V
		• Cerebriform pattern (14.3%)	• Lines, curved and thick	• NS
		• Yellow to grey background (42.8%)	• Structureless, yellow-gray	• NS
		• Yellow to yellow-white homogenous area (42.8%)	• Structureless, yellow, yellow-white	• NS
		• Ovoid nest (42.8%)	• Clods, large	• Keratin-filled epidermal invagination
		• Linear irregular crypts (28.6%)	• Lines, curved and thick, in combination with clods	• NS
		• Milia-like cysts (14.3%)	• Dots or clods, white, clustered or disseminated	• NS
		• Hairpin vessels (14.3%)	• Looped vessels	• NS
		• Linear vessels (14.3%)	• Linear vessels	• NS
Nodular hidradenoma	Behera B, et al. 202121	• White to grey structureless area (100.0%)	• Structureless, white-gray	• NS	Nonpolarized/x10	1	CR	V	IV, V
		• Scales (100.0%)	• NA	• NS
		• Erosion (100.0%)	• Erosions/ulcerations	• NS
		• Blue-grey peppering (100.0%)	• Dots, gray or blue	• NS
		• Polymorphous vascular pattern (linear, linear branching and linear curved (hairpin) vessels (100.0%)	• Polymorphous vessels	• NS
Pilomatrixoma	Behera B, et al. 202121	• Skin-colored to yellow homogenous area (100.0%)	• Structureless, brown/yellow	• NS	Nonpolarized/x10	1	CR	V	IV, V
		• Pigment network-like area (100.0%)	• Lines, reticular	• NS
Poroma	Behera B, et al. 202121	• Diffuse white structureless area (100.0%)	• Structureless area, white	• NS	Nonpolarized/x10	4	CS	V	IV, V
		• Focal yellow to yellow-brown structureless area (50.0%)	• Structureless, yellow/yellow-brown	• NS
		• Brown to blue-gray blotch (25.0%)	• Structureless zone, brown or blue-gray	• NS
		• Branched vessels with a round ending (100.0%)	• Branched vessels	• NS
		• Linear vessels (50.0%)	• Linear vessels	• NS
		• Hairpin vessel (50.0%)	• Looped vessel	• NS
		• Polymorphous vascular pattern (50.0%)	• Polymorphous vessels	• NS
Reactive eccrine syringofibroadenoma	Behera B, et al. 202121	• Grey to greyish-white structureless area separated by white collarette (100.0%)	• Structureless, gray/gray-white	• NS	Nonpolarized/x10	2	CS	V	IV, V
		• Cobblestone pattern (100.0%)	• Clods, large and polygonal	• NS
		• Yellow-white crust (NS)	• NA	• NS
Sebaceous adenoma	Behera B, et al. 202121	• Yellow to yellow-brown homogenous area (100.0%)	• Structureless, yellow/yellow-brown	• NS	Nonpolarized/x10	1	CR	V	IV, V
		• Blue-grey globule (100.0%)	• Clods, small, round or oval (blue-grey)	• NS
		• Fine brown peppering (100.0%)	• Dots, brown	• NS
		• Linear vessels (100.0%)	• Linear vessels	• NS
Sebaceous hyperplasia	Behera B, et al. 202121	• Yellow to yellow-brown homogenous area (100.0%)	• Structureless, yellow/yellow-brown	• Increased basal pigmentation along with sebaceous gland proliferation	Nonpolarized/x10	26 lesions from 6p atients	CS	V	IV, V
		• Single to multiple puncta (100.0%)	• NA	• Sebaceous duct opening
		• Crown vessels (46.2%)	• Linear vessels, radial	• NS
		• Linear branching vessels (3.8%)	• Branched vessels	• NS
		• Fine brown to blue-grey peppering (30.8%)	• Dots, gray or blue	• NS
	Ankad BS, et al. 201715	• Yellow globules (NS)	• Clods, yellow	• NS	Polarized-nonpolarized/NS	2	CS	V	NS (“Brown skin”)
		• Crown vessels (linear vessels running from periphery to the centre) (NS)	• Linear vessels, radial	• NS
		• Pale yellow globules surrounded by pale white septa (NS)	• Clods, yellow	• NS
		• Patulous follicles (NS)	• NA	• NS
Trichoblastoma	Behera B, et al. 202121	• Skin-colored homogenous area (100.0%)	• Structureless, brown	• NS	Nonpolarized/x10	1	CR	V	IV, V
		• Milia-like cysts (100.0%)	• Dots or clods, white	• NS
		• Focal white homogenous area (100.0%)	• Structureless, white	• NS
Trichoepithelioma (familial)	Behera B, et al. 202121	• Skin-colored homogenous area with milia-like cysts (100.0%)	• Structureless zone, brow + dots or clods, white, clustered or disseminated	• NS	Nonpolarized/x10	4	CS	V	IV, V
		• Focal white homogenous area (50.0%)	• Structureless zone, white	• NS
		• Arborizing vessels (50.0%)	• Branched vessels	• NS
		• Linear vessels (75.0%)	• Linear vessels	• NS
		• Crown vessels (25.0%)	• Linear vessels, radial	• NS
		• Fine brown peppering (100.0%)	• Dots, brown	• NS
Trichoepithelioma (solitary)	Behera B, et al. 202121	• Skin-colored to white homogenous area (100.0%)	• Structureless, brown/white	• NS	Nonpolarized/x10	6 lesions from 5 patients	CS	V	IV, V
		• Milia-like cysts (100.0%)	• Dots or clods, white, clustered or disseminated	• Dermal keratocysts
		• Fine brown peppering (33.3%)	• Dots, brown	• NS
		• Linear vessels (16.6%)	• Linear vessels	• NS
Vascular tumors
Angiofibroma	Jindal R, et al. 202122	• Yellow-white dots (100.0%)	• Dots, yellow-white	• Follicular hyperkeratosis	Polarized/x10	4 (facial)	CS	V	NS (“Skin of color”)
		• Brown to reddish-brown background (100.0%)	• Structureless, brown, red-brown	• Increased number of dermal vessels + melanocytic hyperplasia
		• Unfocused vessels (100.0%)	• NA	• Dermal vessels
		• Unevenly distributed specks/dots of brown pigmentation (100.0%)	• Dots, brown	• Dermal melanophages
		• Surface crypts (NS)	• Lines, curved and thick, in combination with clods	• Pseudo-follicular openings
	Ankad BS, et al. 201715	Facial			Polarized-nonpolarized/NS	4 (facial and penile)	CS	V	NS (“Brown skin”)
		• Bluish white lacunae (NS)	• Clods, blue-white	• NS
		• Red dots (NS)	• Vessels, dots	• NS
		• White globules (NS)	• White clods, small, round or oval	• NS
		Penile
		• White globules	• White clods, small, round or oval	• NS
		• Whitish red or pinkish background	• Structureless zone, pink/red	• NS
	Behera B, et al. 202121	• Yellowish-white dots (100.0%)	• Dots, yellow-white	• Follicular hyperkeratosis + sebum	Nonpolarized/x10	1 (facial)	CR	V	IV
		• Pinkish-gray background (100.0%)	• NA	• Vessels + pigmentary
		• Crypts over the surface (NS)	• Lines, curved and thick, in combination with clods	• Pseudofollicular openings
Angiokeratoma	Ankad BS, et al. 201715	• Pink to purplish lagoons (100.0%)	• Clods, red-purple	• NS	Polarized-nonpolarized/NS	1	CR	V	NS (“Brown skin”)
		• Whitish ground glass film (100.0%)	• NA	• NS
		• Thick septae separating each lacuna (100.0%)	• Lines, white	• NS
Cherry angioma	Ankad BS, et al. 201715	• Red to purplish round to oval lagoons (100.0%)	• Clods, red or purple	• NS	Polarized-nonpolarized/NS	10	CS	V	NS (“Brown skin”)
		• Milky-white veil in older lesions (NS)	• NA	• NS
		• A rim of pigment network (20.0%)	• Lines, reticular (peripheral), brown	• NS
Infantile hemangioma	Kusari A, et al. 202123	• Red lacunae (100.0%)	• Clods, red or purple	• NS	NS/NS	1	CR	V	NS (Literature from South Sudan)
		• White septa (100.0%)	• Lines, white	• NS
Lymphangioma circumscriptum	Ankad BS, et al. 201715	• Pale pink lacunae (NS)	• Clods, red or purple	• NS	Polarized-nonpolarized/NS	3	CS	V	NS (“Brown skin”)
		• Pale yellow lacunae (NS)	• Clods, yellow	• NS
		• Purplish globules (NS)	• Clods, red or purple	• Blood
		• White areas (NS)	• Structureless zone, white	• Hyperkeratosis
Pyogenic granuloma	Ankad BS, et al. 201715	• Reddish homogeneous areas (NS)	• Structureless zone, red	• Dilated vessels	Polarized-nonpolarized/NS	39	CS	V	NS (“Brown skin”)
		• White collarette (NS)	• NA	• NS
		• White rail line (NS)	• Lines, white	• NS
		• Vascular structures (NS)	• Vessels	• Collagen bundles separating vascular lobules in the dermis
Connective tissue tumors
Dermatofibroma	Kelati A, et al. 201724	• Network (79.0%) (peripheral 45.8%; patchy 17.7%; total 15.5%)	• Lines, reticular (peripheral, multifocal, uniform)	• NS	Polarized-nonpolarized/NS	100 lesions from 95 patients	CS	V	IV (94%), V (6%)
		• White patches (70.0%) (central scar- like 40.0%; eccentric multiples 30.0%)	• Structureless zone, white (central, multifocal)	• NS
		• Homogeneous pigmentation (36.0%) (central 26.9%; eccentric 3.3%; peripheral 5.8%)	• Structureless zone, brown (central, eccentric, peripheral)	• NS
		• Homogenous pink color (21.1%)	• NA
		• Globule-like structures (18.0%)	• Clods, small, round or oval	• NS
		• White streaks (18.0%)	• Lines, white, perpendicularly	• NS
		• Peripheral rings (13.0%) (around an ulceration 5.5%; around the follicular openings 2.2%, simple ring 5.3%; brown 10.0%; white 3.0%)	• NA	• NS
				• NS
		• Ulceration (6.0%)	• Erosions/ulcerations	• NS
		• Brown streaks (6.0%)	• Lines, radial	• NS
		• Ring-like structures (3.0%)	• NA	• NS
		• Comedo-like opening (3.0%)	• Clods, brown, yellow, or orange (rarely black)	• NS
		• Negative network-like appearance (3.0%)	• Lines, reticular, hypopigmented, around brown clods	• NS
		• Heterogeneous pigmentation (3.0%)	• NA	• NS
		• Milia-like cysts (2.0%)	• Dots or clods, white, clustered or disseminated	• NS
		• Vascular structures (30.0%) (comma-like vessels 23.3%; dotted vessels 23.3%; linear (13.3%)	• Vessels (curved, dots, linear)	• NS
	Ankad BS, et al. 201715	• Central white scar like areas (NS)	• Structureless zone, white (central)	• NS	Polarized-nonpolarized/NS	6	CS	V	NS (“Brown skin”)
		• Central yellow homogeneous areas (NS)	• Structureless zone, yellow (central)	• NS
		• Delicate peripheral pigment network (NS)	• Lines, reticular and thin	• NS
		• Peripheral striations (NS)	• Lines, radial (peripheral)	• NS
		• Central, distorted pigment network (16.7%)	• Lines, reticular and thick or reticular lines that vary in color	• NS
	Giddens T, et al. 202225	• Central, brown, homogeneous area (60.0%)	• Structureless zone, brown (central)	• NS	Polarized/NS	5 lesions from 3 patients	CS	V	V,VI
		• Central hyperpigmented area with blue white color (20.0%)	• Structureless zone, blue-white (central)	• NS
		• Peripheral reticulation (20.0%)	• Lines, reticular and thin (peripheral)	• NS
		• Peripheral pigment network (60.0%)	• Lines, reticular and thin (peripheral)	• NS
		• Uniformly distributed brown network (20.0%)	• Lines, reticular and thin	• NS
		• Absent central white scar (100.0%)	• NA	• NS
	De Giorgi V, et al. 200611	• White central patch (100.0%)	• Structureless zone, white (central)	• NS	NS/NS	1	CR	V	NS (“Black people”)
		• Fine peripheral network (100.0%)	• Lines, reticular and thin (peripheral)	• NS
	Piccolo V, et al. 201626	• Atypical network (100.0%)	• Lines, reticular and thick or reticular lines that vary in color	• NS	NS/NS	1	CR	V	NS (“African man”)
		• Hyper- and hypopigmented structureless areas (100.0%)	• NA	• NS
		• Shiny white streaks (100.0%)	• Lines, white, perpendicularly
		• Unfocused linear-irregular vessels (100.0%)	• Serpentine vessels
	Escobar GF, et al. 201927	• Pigmented network with interruptions (100.0%)	• NA	• NS	NS/x20	1	CR	V	IV
		• Pinkish background (100.0%)	• NA	• NS
Fibrokeratoma	Ankad BS, et al. 201715	• Homogeneous brownish-white and rosy-white area (NS)	• Structureless zone, white-brown, pink-white	• NS	Polarized-nonpolarized/NS	5	CS	V	NS (“Brown skin”)
		• Dotted vessels (NS)	• Vessels, dots	• NS
		• Linear vessels (NS)	• Linear vessels	• NS
		• White structureless (tree branches- like arrangement) (NS)	• Structureless zone, white	• Fibrous tissue in the dermis
Neurofibroma	Ankad BS, et al. 201715	• Pink-red homogeneous areas (NS)	• NA	• NS	Polarized-nonpolarized/NS	4	CS	V	NS (“Brown skin”)
		• Peripheral pigment network (NS)	• Lines, reticular (peripheral)	• NS
		• Fissures (NS)	• NA	• NS
		• Scar-like white areas with starburst appearance (NS)	• Structureless zone, white	• NS
Cystic neoplasms and others
Epidermal cyst	Ankad BS, et al. 201715	• Yellow and black-colored pore (NS)	• NA	• NS	Polarized-nonpolarized/NS	7	CS	V	NS (“Brown skin”)
		• Branching vessels (NS)	• Branched vessels	• NS
		• Ivory white homogeneous area (NS)	• Structureless zone, white	• NS
	Behera B, et al. 202121	• Yellow homogenous area (25.0%)	• Structureless, yellow	• NS	Nonpolarized/x10	4 lesions from 1 patient	CS	V	IV,V
		• Grey homogenous area (25.0%)	• Structureless, gray	• NS
		• Central punctum surrounded by grey homogenous area (25.0%)	• NA	• NS
		• Skin-colored homogenous area (25.0%)	• Structureless zone, brown	• NS
Milia	Ankad BS, et al. 201715	• White to yellow homogeneous areas. (NS)	• Structureless, white/yellow	• NS	Polarized-nonpolarized/NS	3	CS	V	NS (“Brown skin”)
		• Brownish peripheral rim (NS)	• NA	• NS
		• Linear vessels (NS)	• Linear vessels	• NS
Trichilemmal cyst	Behera B, et al. 202121	• Skin-colored homogenous area (40.0%)	• Structureless, brown	• NS	Nonpolarized/x10	5	CS	V	IV, V
		• White homogenous area with arborizing vessels (20.0%)	• Structureless, white + branched vessels	• NS
		• Central scar-like or white homogenous area with peripheral brown homogenous area/fingerprint- like area (20.0%)	• Structureless zone, white (central or uniform) +/− structureless zone, brown/ lines, brown, curved, parallel, thin	• NS
		• Central scar-like/white homogenous area surrounded by fingerprint-like area (20.0%)	• Structureless zone, white(central) +/− lines, brown, curved, parallel, thin	• NS
		• Peppering (20.0%)	• Dots, gray, blue or black	• NS
Steatocytoma multiplex	Ankad BS, et al. 201715	• Yellow homogeneous area covering entire lesion (NS)	• Structureless, yellow	• NS	Polarized-nonpolarized/NS	1	CR	V	NS (“Brown skin”)
		• Linear vessels (NS)	• Linear vessels	• NS
		• Peripheral brown rim (NS)	• NA	• NS
		Classic MF (N=4; 18 images)
Mycosis fungoides (MF)	Nakamura M, et al. 202128	• Dark brown to gray or black clods and dots forming pseudonetworks (NS)	• Clods/dots, brown-gray or black	• NS	NS/NS	11 (33 dermoscopic images)	CS	V	IV-VI
		• Thick black lines (NS)	• Lines, reticular and thick	• NS
		• Erythematous to whitish pink, structureless zones (NS)	• Structureless, red/white	• NS
		• Prominent eccrine duct openings (NS)	• NA	• NS
		• White rosettes (NS)	• Dots, white, four arranged in a square	• NS
		• Geometric white lines (NS) Hypopigmented MF (N=4; 9 images)	• Lines, reticular, white	• NS
		• Patchy, amorphous, white-pink areas (NS)	• Structureless, white-pink	• NS
		• Reduction or loss of natural pigment network (NS)	• NA	• NS
		Folliculotropic MF (N=1; 4 images)
		• Follicular plugging (NS)	• Follicular plugs	• NS
		• Perifollicular scale (NS)	• NA	• NS
		• Hyperpigmented to violaceous perifollicular halos (NS)	• NA	• NS
		Verrucous MF (N=2; 2 images)
		• Large, multicolored amorphous structures (NS)	• NA	• NS
		• Yellow-gray ridges (NS)	• Lines, curved and thick, yellow-gray	• NS
		• Comedo-like openings (NS)	• Clods, brown, yellow, or orange (rarely black)	• NS

NA: Not applicable; NS: Not specified; CR: Case report; CS: Case series; C-C: Case-control study