Porokeratotic Variant of Lichen Planus

A 44-year-old woman presented with mildly itchy, brownish-black plaques for the last 2 years. The lesions first appeared on the upper back, followed by involvement of the face and upper arms within 4-5 months. Individual lesions began as small papules that gradually evolved into small, annular, and barely palpable plaques. There were no systemic complaints, photosensitivity, or history of intake of prolonged medication. Cutaneous examination revealed multiple, well-demarcated, and hyperpigmented oval to round plaques on the photo-exposed area, including the face, bilaterally on arms, and upper trunk, measuring about 1 × 1-3 × 3 cm² in size (Figures 1A and 1B). Dermatoscopic examination established rolled-out, thread, double-marginated border with central atrophy with a brownish reticular background. Multiple brownish to black globules and dark lacunae were also observed (Figures 1C and 1D). No Wickham's striae were viewed. Combination of clinical presentation with dermatoscopic findings indicated a provisional clinical diagnosis of disseminated superficial porokeratosis. Biopsy performed on the upper back revealed hyperkeratotic epidermis with mild lymphocytic exocytosis and spongiosis with pigmentary incontinence. The coronoid lamina was not revealed in any of the pathologic sections examined, including further deeper sections and in a repeat biopsy. Clinical morphology, dermatoscopic features, and pathology were considered compatible with the diagnosis of porokeratotic variant of lichen planus (LP). The patient was counseled and started on topical steroids (fluticasone). She is on regular follow-up.