Porokeratoma is a recently described solitary or multiple tumor-like acanthoma, sharing the histological feature of cornoid lamellae with porokeratosis. Whether porokeratoma is a variant of porokeratosis is controversial. We report a rare case of a 53-year-old Chinese woman who presented with multiple, symmetrical, hemispherical and verrucous plaques on her lower extremities that had been present for 20 years. The clinical manifestation resembled the fungal disease of chromoblastomycosis. The diagnosis of multiple porokeratoma coexisting with disseminated superficial porokeratosis was rendered according to the clinical, dermoscopic and pathological features. Oral acitretin (30 mg/day) and laser therapy were administrated. After 6 months of treatment, the number of plaques on her limbs was significantly reduced without recurrence. From this case, we speculate that porokeratoma is a rare and special variant of porokeratosis. In complex cases with multiple lesions, oral acitretin can be combined with surgery, cryotherapy and laser therapy.
Keywords: acitretin; cornoid lamellae; dermoscopy; disseminated superficial porokeratosis; porokeratoma.
© 2020 Japanese Dermatological Association.