Ultraviolet-Induced Fluorescence Dermoscopy: Game Changers

Abstract

Ultraviolet-induced fluorescence dermoscopy (UVFD) is a novel diagnostic and visualization technique that enhances visualization of skin dermatoses with ultraviolet (UV) light. UVFD has been used to diagnose dermatoses including bacterial and fungal infections, pigmentary disorders, and skin neoplasms. We present five cases—pitted keratolysis, porokeratosis, molluscum, biopsy site identification, and lentigo maligna—where UVFD alone, compared to traditional polarized dermoscopy (PD) or the unaided clinical exam, served as a "game-changer" in diagnosis and management. Polarized and UV images were captured using a DL5 dermatoscope coupled to a smartphone. In the cases of pitted keratolysis, porokeratosis, and molluscum, we highlight distinct patterns of fluorescence that were readily visualized with UVFD and aided efficient diagnosis, in contrast with more subtle features that were seen under PD. We also demonstrate the utility of UVFD in identification and confirmation of a prior biopsy site in a patient who presented for excision of a skin cancer. Finally, we describe the advantage of UVFD in presurgical margin delineation in a patient with lentigo maligna. In these cases, we show that UVFD facilitates prompt and accurate diagnosis, streamlines appropriate treatment, and has the capacity to reduce the need for unnecessary biopsies. Given the convenience and practicality of a dermatoscope equipped with a UV light, we propose that clinicians would benefit from the use of UVFD as a supplementary tool alongside conventional dermoscopy, rather than as a substitute.

Ultraviolet-induced fluorescence dermoscopy (UVFD) is a novel diagnostic and visualization technique.^1–13 Building upon the advantages of traditional polarized dermoscopy (PD), UVFD enhances visualization of skin dermatoses with ultraviolet (UV) light in a handheld, portable format. Similar to the conventional Wood’s lamp, which emits light at wavelengths ranging from 320 to 400nm, UVFD utilizes high-energy, short-wavelength light emitting diodes (peak wavelength 365nm, 10mW/cm²), to stimulate skin chromophores.^1,2 The accumulated energy, eventually emitted as a photon in the visible light spectrum, is then detectable by the human eye due to the Stokes shift effect.¹

The Wood’s lamp has long been used for diagnosis of several dermatoses, including bacterial and fungal infections, pigmentary disorders, and cutaneous porphyrias, as well as for identification of skin neoplasm margins.² Thus, its integration with dermoscopy might prove an invaluable supplement to traditional dermoscopic evaluation. Recent literature elucidates the advantages of UVFD for diagnosing and monitoring scabies, vitiligo, alopecia, seborrheic keratoses, pityriasis versicolor, and melanoma.^3–10

We present five cases where UVFD alone, compared to traditional PD or the unaided clinical exam, served as a "game-changer" in diagnosis and management. In these cases, a commercially available UVFD dermatoscope (DermLite DL5; DermLite, LLC) coupled to a smartphone was utilized to produce and capture the fluorescent images. All patients provided informed consent and photoconsent.

Pitted keratolysis. A 23-year-old male patient presented with concern regarding years of malodorous feet. He was previously treated with oral terbinafine without improvement. Physical examination revealed multiple punctate, crateriform pits on the right plantar foot and maceration in the interdigital spaces (Figure 1A). Ultraviolet fluorescence (UVF) revealed a coral-red color (Figure 1B), consistent with Corynebacterium spp. pitted keratolysis. In this case, the responsible fluorochrome is Coproporphyrin III, which appears as an orange-red color under UVF. As a result, he was properly diagnosed and treated with topical clindamycin gel and oral doxycycline.

Figure 1.

Pitted keratolysis. (A) Clinical exam showed crateriform plantar pits. (B) Examination with ultraviolet fluorescence (UVF) revealed bright coral-red fluorescence of the plantar surface.

Porokeratosis. A 62-year-old female patient with history of basal cell carcinoma (BCC) and actinic damage presented to clinic for a full-body skin exam. A 0.5cm tan, scaly thin plaque on her right lateral thigh was seen (Figure 2A). PD showed a subtle yellow-to-light brown peripheral keratin rim (black arrow, Figure 2B) on an otherwise unremarkable image. Under UVFD, the keratin rim (coronoid lamella) showed a bright blue-green fluorescence (black arrow, Figure 2C), revealing a "diamond necklace" appearance.^12,14 While an ink test would also enhance this feature, the use of UVFD minimizes the additional time and effort needed to confirm the diagnosis.

Figure 2.

Porokeratosis. (A) Clinical exam showed a thin plaque with a subtle brown peripheral keratin rim. (B) Examination with contact polarized dermoscopy (PD) showed a faint yellow-to-light brown color along the peripheral keratin rim. (black arrow) (original magnification ×10). (C) Examination with ultraviolet-induced fluorescence dermoscopy (UVFD) revealed a “diamond necklace” pattern of blue-green fluorescence along the keratin rim (black arrow) (original magnification ×10).

Molluscum. A 16-year-old male patient presented with several small, pink and brown monomorphous papules on the arms and legs (Figure 3A). PD showed a central white clod (keratotic papule) superimposed on a white-yellow homogeneous background (Figure 3B). While traditional PD did not readily display the characteristic central umbilication with polylobular yellow-to-white amorphous structures, or fine, branched vessels, UVFD strikingly highlighted the bright white umbilicated center (Figure 3C).^9,15–18

Figure 3.

Molluscum. (A) Clinical exam showed uniform pink and brown papules. (B) Examination with contact PD showed a central white clod overlying the umbilicated center (original magnification ×10). (C) Examination with UVFD revealed bright white fluorescence of the umbilicated center (original magnification ×10).

Biopsy site identification. A 68-year-old male patient presented for surgical excision of a previously biopsied BCC of his right scapular back (Figure 4A). Due to the unlabeled clinical photo, numerous lentigines, and unclear anatomic positioning for surgery, dermoscopy was utilized to confirm the biopsy site. While PD demonstrated a subtle white-pink background with overlying vessels (Figure 4B), UVFD revealed a prominent 0.8cm area of darkening compared to the patient’s surrounding skin, confirming the biopsy site (white arrow; Figure 4C). The enhanced darkening likely reflects post-biopsy scar tissue, as well as increased inflammation and hypervascularity.¹¹

Figure 4.

Biopsy site identification. (A) Clinical exam of a patient presenting for excision of a previously biopsied basal cell carcinoma (BCC). (B) Examination of the biopsy site with contact PD showed vessels overlying a white-pink patch (original magnification ×10). (C) The biopsy site was confirmed with UVFD, which revealed prominent darkening (white arrow) relative to surrounding skin (original magnification ×10).

Lentigo maligna margin delineation. A 65-year-old female patient presented with an irregular pigmented patch measuring 1.3 x 1.4cm located on her left medial cheek (Figure 5A). PD showed asymmetric follicular pigmentation and arborizing vessels at the periphery that reflect scar tissue in the setting of a prior biopsy (as opposed to melanoma) (Figure 5B). UVFD revealed an overall darkening of the lesion with accentuation of the lesion borders (Figure 5C). This was signified by the contrast between the darker and light areas of absorption. As a result, UVFD served as a complement to the melanoma-specific features visualized under PD by increasing border visibility, thus allowing for better estimation of subclinical extension and presurgical margin delineation.

Figure 5.

Lentigo maligna. (A) Clinical presentation of a patient with an irregular pigmented lesion on the cheek. (B) Examination with contact PD showed asymmetric follicular pigmentation. There is also an area of prior biopsy (original magnification ×10). (C) Examination with UVFD revealed darkening of the pigmented lesion which allowed for enhanced visibility of the lesion’s borders (original magnification ×10).

DISCUSSION

The highlighted cases represent "game changers" where the use of UVFD demonstrated improved diagnostic capability over traditional PD or the unaided clinical exam. The addition of UVFD effectively and efficiently identifies diagnostic features that might be not visible when examined solely with conventional dermoscopy. Given the practicality of a dermatoscope equipped with a UV light, clinicians would benefit from the use of UVFD as a supplementary tool alongside conventional dermoscopy, rather than as a substitute. As in the aforementioned cases, there is minimal time and effort required for the incorporation of UVFD. UVFD facilitates prompt diagnosis, streamlines appropriate treatment, and has the capacity to reduce the need for unnecessary biopsies.