A 49-year-old white male presented with well-circumscribed lesions on both the upper and lower extremities of 10 years duration. The lesions were slowly increasing in size and number, without any associated symptoms. He was a construction worker and spent most of his time outdoors. His past health was unremarkable and he was not on any medications. He believed that his father, now passed away, may have had similar skin lesions.
Porokeratosis is a disorder of keratinization, characterized clinically by centifugally enlarging macules or patches with central atrophy, raised hyperkeratotic borders, and histologically, by a distinctive hyperkeratotic ridge-like border (cornoid lamella). The disorder was first described by Vittorio Mibelli in 1893 and now bears his name.