Ultraviolet-Induced Fluorescence Dermoscopy of Porokeratosis

In the current era, where dermoscopy has become an indispensable tool in dermatology, adding an ultraviolet (UV) light source, that emits 365 nm light, makes it more useful for diagnosing and monitoring dermatological diseases with visible fluorescence in skin lesions. UV-induced fluorescence dermoscopy (UVFD) provides better and more precise images than polarised dermoscopes in identifying multiple dermatological conditions.[1] This article discusses the utilization of UV-induced fluorescence dermoscopy in porokeratosis. Porokeratosis is a type of keratinization disorder with an unidentified etiology, varied clinical presentation, and distinctive histopathology. It generally does not respond to most therapeutic options. This clonal keratinization abnormality is thought to be caused by defects in the mevalonate pathway.[2] Porokeratosis is typically classified as either localized or generalized. Common localized variants include classical porokeratosis of Mibelli, linear porokeratosis, punctate porokeratosis, solar facial porokeratosis, and genital porokeratosis. Generalized variants include disseminated superficial porokeratosis, disseminated superficial actinic porokeratosis, and disseminated palmoplantar porokeratosis. Uncommon types include hyperkeratotic porokeratosis, eruptive pruritic papular porokeratosis, verrucous porokeratosis (localized to buttocks), and reticulate porokeratosis. The classic variant is distinguished by isolated plaques characterized by a thread-like hyperkeratotic margin, most frequently found on the extremities [Figure 1].Figure 1: The clinical image showing multiple pigmented macules on the face (red circle – lesion on which dermoscopy was performed)Cornoid lamella, a densely packed thin column of parakeratotic cells above a zone of focal hypogranulosis, is the histologic hallmark. Another reproducible finding is lymphocytic inflammation with variable density, typically found in the papillary dermis. Dyskeratotic keratinocytes may be found beneath the spinous layer.[3] The papillary dermis underneath the cornoid lamella has a moderately dense inflammatory infiltrate and dilated capillaries. The cornoid lamella can extend through the hair follicles and intraepidermal eccrine sweat gland ducts. Porokeratosis dermoscopy typically shows a central white scarring area, red-brown dots and globules, and various patterned vessels with a white peripheral border, which is often double-marginated and represents coronoid lamella. This has been referred to as keratin rim. Other eponyms used are “white track”, “double white tract”, and “lines of volcanic crater” [Figure 2]. This is a specific clue for porokeratosis.[4] However, this keratin rim may sometimes not be easily visualized and become more pronounced on UVFD, revealing a blue-white ring known as a ‘diamond necklace’ at the border of these lesions [Figure 3].[5] Therefore, UVFD improves diagnostic accuracy, which is often overlooked in dermoscopy under polarized settings.Figure 2: Polarized dermoscopy of the lesion showing an annular lesion of light brown colour (Green star) with sparing of adnexal opening (Red arrow) (Dermlite DL5/polarized mode/10×)Figure 3: UV-induced fluorescence dermoscopy of the lesion showing a blue-white annular ring (yellow arrow) around the lesion (Dermlite DL5/UV mode/10×)Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initial will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. Use of AI The authors confirm that there was no use of artificial intelligence (AI).