Trichoscopy of Discoid Lupus Erythematosus in Caucasian Scalp: A Review

Abstract

Background

Scalp discoid lupus erythematosus in Caucasians is still a rare disease with a variable clinical presentation. Its dermoscopic characteristics are poorly described in literature, especially in the white population. The aim of this review was to critically analyze published papers on this topic and summarize relevant features.

Summary

A comprehensive search for eligible articles was conducted in the databases of MEDLINE/PubMed. Results were analyzed following dermoscopic patterns such as follicular openings, hair shafts, perifollicular surface, and vessel pattern.

Key Messages

The most representative features appeared the absence of follicular openings and the presence of follicular keratotic plugs, along with yellow-brown and red dots. In long-lasting lesions with chronic stage, trichoscopy showed the absence of follicular openings, white or milky red cicatricial patches, white and brown structureless areas, and thick arborizing vessels.

Introduction

Lupus erythematosus is an autoimmune disease that causes widespread inflammation and tissue damage in the affected organs, including the skin. Discoid lupus erythematosus (DLE) represents the most common subtype of chronic cutaneous lupus erythematosus, accounting for 50–85% of cases [1]. It is estimated that 15 to 30 percent of patients with systemic lupus erythematosus (SLE) develop DLE [2]. Scalp is the most affected site by DLE, with reported involvement in 30–50% of cases [3]. The aim of this review was to summarize the most frequent dermoscopic features in Caucasians.

We reviewed articles published in PubMed between 2000/1/1 and 2023/7/31 using the terms “discoid lupus erythematosus,” “trichoscopy,” and “dermoscopy.” We limited our search to the English literature and excluded duplicated titles. We considered the largest studies focusing on trichoscopy of DLE in the Caucasian scalp.

We found 31 relevant articles, which included 15 literature reviews, 9 clinical studies, and 7 case reports. Focusing on studies concerning scalp discoid lupus in Caucasian patients, however, we considered only 5 literature reviews consistent with our research [4–8]. Comparative results are summarized in Table 1.

Table 1.

Dermoscopic features of scalp DLE in Caucasians analyzed by trichoscopic subcategories

	Karadag Köse et al. [4], n (%)	Lanuti et al. [5], n (%)	Gomez et al. [6], n (%)	Lallas et al. [7], n (%)	Golinska et al. [8], n (%)
Patients, n	7	3	55	28	157
Follicular openings
Absence of follicular openings	7 (100)	1 (33.3)			29 (18.5)
Follicular keratotic plugs		3 (100)	19 (34.5)	19 (67.9)	70 (44.6)
Yellow dots	3 (43)	1 (33.3)	11 (20)
Black dots			16 (29.1)
White dots	2 (28.6)	1 (33.3)	40 (72.7)		43 (27.4)
Red dots	2 (28.6)		8 (14.5)	1 (3.6)	46 (29.3)
Blue-gray dots			12 (21.8)
Dilated follicles				14 (50)
Hair shafts
No vellus	2 (28.6)
Short vellus	1 (14.3)
Broken hair	1 (14.3)		8 (14.5)
Tufted hair
Pili torti	1 (14.3)		4 (7.3)
Perifollicular surface
Pink-white appearance	7 (100)	3 (100)	50 (90.9)	9 (32.1)
Honeycomb pattern	1 (14.3)
Brown scattered pattern	2 (28.6)	1 (33.3)	33 (60)	12 (42.9)
Crust formation	1 (14.3)
Interfollicular scaling	6 (85.7)		35 (63.6)	9 (32.1)
Perifollicular scaling	3 (42.9)	1 (33.3)	46 (83.6)		64 (40.8)
Peripilar cast	1 (14.3)
Yellowish tubular scaling			3 (5.4)	1 (3.6)
Perifollicular erythema			8 (14.5)	19 (67.9)
Blood vessels
Arborizing red lines	3 (42.9)		37 (67.3)		65 (41.4)
Linear vessels				15 (53.6)
Coiled vessels			2 (3.6)
Polymorphous vessels		1 (33.3)

Epidemiology

Scalp DLE age of onset is usually between 20 and 40 years and has a higher incidence and prevalence in women of African descent [9]. As reported by Adrienne et al. Caucasians people tend to gain lower scores on specific disease index (CLASI – Cutaneous Lupus Activity Severity Index) compared to African-Americans [10]. Interestingly, although scalp DLE being more frequent in women, the tendency to develop the scarring form maintains an equal proportion in both genders [11].

Clinical Presentation

Scalp is the most affected site by DLE, with reported involvement in 30–50% of cases [2]. Clinical presentation can be variable. Active stage of the disease is characterized by the presence of one or multiple erythematous violaceous skin plaques with typical follicular keratotic plugs. The most common localizations of DLE are face, ears, and scalp, resulting in a form of scarring alopecia (Fig. 1, 2). DLE can occur either in association with systemic disease or independently. The scalp is a frequently affected site where the disease presents with one or more well-demarcated alopecic inflammatory plaques, characterized by a pink to bright red color, with skin atrophy, loss of follicular ostia, follicular plug, and adherent scales. Other signs frequently present are edema, erythema, and other signs of active inflammation. Desquamation may be diffuse or localized around the follicle, with numerous hyperkeratotic plugs. In a minority of patients, DLE may initially manifest as diffuse desquamation of the scalp with adherent scales mimicking psoriasis [1]. As DLE is a major cause of primary scarring alopecia early recognition and treatment of the condition is essential to avoid disfiguring scarring with permanent hair loss.

Fig. 1.

Clinical presentation of DLE of the scalp.

Fig. 2.

Trichoscopy of dilated infundibula filled with keratin plugs (Fotofinder medicam ×800HD, ×20 magnification, dry mode).

Trichoscopy

Dermoscopy can help clinicians to make the correct diagnosis, thus enabling targeted treatment from the earliest stages. The different stages of the lesions correspond to specific trichoscopic features. In active lesions, the presence of yellow-brown and red dots can be detected (Fig. 3), while in long-lasting lesions with inactive pathology, trichoscopy shows the absence of follicular openings, white or milky red cicatricial patches, white and brown structureless areas, and thick arborizing vessels (Fig. 4) [12].

Fig. 3.

Trichoscopy of active lesion with presence of yellow-brown (squared) and red dots (encircled) (Fotofinder medicam ×800HD, ×20 magnification, dry mode).

Fig. 4.

Arborizing dilated vessels (squared) with non-follicular red dots in a dotted vessels pattern (encircled) (Fotofinder medicam ×800HD, ×20 magnification with immersion fluid).

For our review, we selected only studies conducted in Caucasian patients, considering that there are no studies comparing clinical and trichoscopic features in white vs. black population. Given that, this study analyses Caucasians’ scalp DLE, focusing on trichoscopic patterns subcategories such as follicular openings, hair shafts, perifollicular surface, and vessels pattern.

Follicular Openings

In scalp DLE, the most common findings are follicular keratotic plugs, corresponding on histopathology to follicular hyperkeratosis and plugging of the follicular ostia filled with keratin. They were firstly associated to an early and active form of DLE, while nowadays their presence has also been detected in chronic lesions. Another common criterion is the absence or reduction of follicular ostia that seems related to DLE lesion duration and usually may not be detected in early stage active DLE lesions [13].

Fibrotic White Dots. Fibrotic white dots are described as irregular structures with blurred edges with a tendency to confluence, resulting in white areas without structure and follicular openings. They are found in most primary scarring alopecias and correspond to vertical fibrotic tracts in histopathology. Fibrotic white spots must be distinguished from pinpoint white spots, linked to eccrine sweat duct openings or empty hair follicle openings, which are smaller, regular in shape, and sharply demarcated from the surrounding skin, often encircled by a hyperpigmented halo [13].

Yellow Dots. Yellow dots are nothing more than follicular ostium filled with sebum or keratotic material. In DLE, yellow dots are usually bigger in dimension and may have a shade of brown color. Nikam et al. [14] reported that yellow dots are best visualized in polarized mode.

Black Dots. Black dots correspond to hair shaft fracture at scalp surface and are related to early disease stages; usually they are related to a disease active phase [13].

Follicular Red Dots. Tosti et al. [15] analyzed this feature for the first time in 2009. Their presence corresponds to dilated infundibula filled with keratin plugs or emerging hair shafts. On histopathology, the correspondence seems to be dilated vessels and red blood cell extravasation. Also, this criterion is better visualized on polarized mode [14]. Follicular red dots were initially considered a prognostic factor in DLE, indicating a high probability of hair regrowth, and were described as a highly specific feature of active scalp DLE. Despite this, red dots were documented in 13.2% of the healthy population and may be linked to richer vascularization of normal hair follicles [13, 16].

Red Spider on a Yellow Dot. The “red spider on a yellow dot” term was introduced by Rakowska et al. [17] to describe thin arborizing vessels overlying large yellow dots. This finding was considered by the authors to be highly specific for long-lasting inactive DLE lesions and is a criterion most easily seen in fair-skinned subjects [13].

Hair Shafts

There are no specific DLE findings, and the following characteristics can be observed also in other types of alopecia. The most frequent hair alterations are the presence of short vellus hair, anisotrichosis, and broken hairs. On the other way, absence of vellus hair in almost 30% of Caucasian patients was also described, and single reports detected pili torti and circular hairs as additional features [4, 13, 18].

Perifollicular Surface

Perifollicular scaling is frequently observed in scalp DLE. Excessive perifollicular scaling may lead to tubular hair cast formation, better observed in polarized mode. Perifollicular pigmentation is a rare trichoscopic sign linked to the presence of black-colored structures around hair shafts at the level of emergences from the scalp.

Hyperpigmentation in dermoscopy is, in fact, related to an altered distribution of melanin and hemoglobin in skin layers and has an histopathologic correlation with pigment incontinence [19, 20]. Perifollicular pigmentation should then be distinguished from the peri-pilar sign, which corresponds to perifollicular lymphocytic infiltrates on histopathology and can be seen as a brown hue around hair follicles [13].

White Structureless Areas. White structureless areas are white patches; they are usually found in end-stage DLE lesions and correspond to diffuse dermal fibrosis on histopathology. On the other hand, lesions of shorter duration may be characterized by pink-white background, a frequent feature reported in scalp DLE plaques, associated with the presence of inflammatory infiltrate and partial fibrosis [13].

Interfollicular Scales. Interfollicular scales corresponds, instead, to hyperkeratosis on histopathology. In the majority of studies, the scales are bright white in color; just one study reported the formation of yellowish scales [6, 13].

Scattered brown Pigmentation. Scattered brown pigmentation was initially reported by Rakowska et al. [17] as a sign of active disease and corresponds to epidermal atrophy along with pigment on histopathology.

White Rosettes. White rosettes are shiny structures composed of four oval-shaped white points connected in the center, looking like four-leaf clover pattern. Initially described as characteristic feature of actinic keratosis, they were reported in scalp DLE for the first time in 2016 [21]. Recent studies report their presence mostly in Caucasians, probably being the effect between polarized light and follicular structure [22].

Chrysalides. Chrysalides has recently been described by Gomez-Quiespe et al. [6] as shiny white lines in scalp DLE, probably related to stromal alterations and fibrosis. Although not specific, they could serve as a diagnostic clue for long-standing DLE.

Honeycomb Pigment Pattern. Honeycomb pigment pattern is frequently seen in Caucasian patients and has been linked to chronic sun exposure of the scalp. Melanin deposits are present in dermal papillae, delineating hypomelanotic areas, and in epidermal ridges, delimiting hyperchromic lines. It is characterized by the presence of hypomelanotic areas, linked to melanin deposits overlying dermal papillae, corresponding to melanin deposits in epidermal ridges. In contrast, in highly active diseases the inflammatory infiltrate could inhibit melanogenesis, resulting in a lack of pigmented network [13].

Vessel Pattern

Arborizing vessels are the most common vascular morphology encountered in DLE, even more frequent in scalp than non-scalp lesions. They are thicker and less regular than those described in basal cell carcinoma. Dotted, hairpin, coiled and polymorphous vessels were observed with low frequencies [13]. Noteworthy, Abedini et al. [23] reported non-follicular red dots in a dotted vessels pattern in 50% of lesions of scalp DLE. Linear vessels were more frequently described in non-scalp DLE. Lallas et al. [7] described this vascularization in more than 50% of Caucasian patients with scalp involvement.

Histopathology

Diagnostic suspect of DLE can be confirmed by histopathology and direct immunofluorescence. One of the most characteristic findings is interface dermatitis with vacuolization of the basal layer, associated with dyskeratotic or apoptotic keratinocytes. Pigment incontinence and epidermal atrophy can be other additional findings. Inflammatory infiltrate is characteristically lymphocytes-based, with sparse plasma cells around vessels, adnexal structures, and interstitium. At direct immunofluorescence a continuous granular pattern is appreciable, with immunoglobulin G, immunoglobulin M, and C3 deposits [12].

Differential Diagnosis

Scalp DLE differential diagnosis should be made with other forms of scarring alopecia, each of which has additional clinical features and specific dermoscopic criteria, thus knowing dermoscopic patterns can help the clinician formulate the correct diagnosis. We summarize below some dermoscopic criteria that can aid in the correct differential evaluation.

• DLE: well-demarcated inflammatory plaques with peripheral accentuation and scaly surface. Scales are adherent, sometimes with follicular plugs and lesions progress into atrophic, dyspigmented scars.

• Lichen plano-pilaris: atrophic areas with perifollicular erythema and hyperkeratosis, usually itching. Edges are “moth-eaten” and there’s a central scalp area predilection.

• Central centrifugal scarring alopecia: centrifugal progression of alopecia on the central scalp affects mainly women of African descent.

• Folliculitis decalvans: pustules, crusts, and tufted hairs emerging from a single inflamed follicle, particularly at the periphery of patches of alopecia.

• Dissecting cellulitis of the scalp: papules, pustules, floating nodules, and abscesses. It has a predilection for black men and formation of sinus tracts is possible.

• Acne keloidalis nuchae: characterized by pustules, papules, and keloid plaques often concentrated on the occipital scalp.

• Tinea capitis: usually presents with multiple small lesions, often surrounded with papules. Children are most affected subjects.

• Performing a scalp biopsy is therefore usually recommended to confirm the nature of scarring alopecia and establish the correct diagnosis [24].

Therapy

Sunscreens, topical, and intralesional corticosteroids are proven to be effective for DLE. Whenever possible patients should be kept in therapy with topical steroids, intralesional corticosteroids, such as triamcinolone acetonide, are also used in DLE [1]. Oral corticosteroids are often used in active phase and then tapered at least on alternate-day to reduce side effects. In addition, calcineurin inhibitors may be of some benefit; however, pharmacological vehicles can be cosmetically uncomfortable on the scalp. Oral antimalarials drugs such as chloroquine and hydroxychloroquine are usually prescribed for maintenance therapy in moderate-severe cases. Antimalarial dose should be weight-based, with a special attention for retinal toxicity and for therapy duration. Treatment duration longer than 5 years has been associated with more side effects, as well as therapy in patients older than 60 years, obese, or with kidney/liver disease. For the ophthalmological risk, a baseline examination and annual monitoring of high-risk patients is highly suggested. Methotrexate and isotretinoin have been found to be effective in some cases of DLE refractory to other treatments. Both hydroxychloroquine and acitretin have been associated with marked improvement or clearing in about half of all people treated, but no drug has been tested against placebo in a randomized clinical trial. Dapsone therapy has been reported as beneficial to some patients, with the warning of screening for glucose-6-phosphate dehydrogenase deficiency and monitoring hemolysis, methemoglobinemia, and neuropathy. The role of biologic drugs such as efalizumab, belimumab, and rituximab, approved for the use in SLE, remains to be ascertained [1]. Single trials reported efficacy of Imiquimod cream 5% and R-salbutamol in cutaneous lesions [25, 26].

Conclusions

Trichoscopy of lupus erythematosus of the scalp in Caucasians is a topic yet to be described. The aim of this review was to critically analyze published papers on this topic and summarize relevant details, focusing especially on trichoscopic features in the white population.

Concentrating on follicular openings, the most representative features appeared the absence of follicular openings and the presence of follicular keratotic plugs, along with yellow-brown and red dots. Regarding hair shafts analysis, instead, no specific characteristic has been highlighted.

Moving to perifollicular surface, pink-white appearance and interfollicular scaling seem to be characteristics of scalp DLE, accompanied by perifollicular scaling and brown scattered pattern. Perifollicular erythema was also sometimes described in a discrete percentage of cases.

Ending with vessels pattern analysis, arborizing red lines, and linear vessels are the most described vascularization features. However, it is important to note the frequent presence in Caucasian patients of white rosettes and honeycomb pigment pattern, a sign of photo exposure and chronic skin photodamage. In this ethnic group, therefore, it is also essential to implement preventive treatment of field of cancerization to avoid the occurrence of skin cancer, in addition to DLE treatment.

Conflict of Interest Statement

The authors have no conflicts of interest to declare.

Funding Sources

This study was not supported by any sponsor or funder.

Author Contributions

E.M. and R.V. prepared the draft, wrote the article, and approved the final version to be published. M.S. conceived the study, critically reviewed the article, and approved the final version to be published.

Funding Statement

This study was not supported by any sponsor or funder.