This 57 year old African-American female presented with a 3-month history of eruptive hyperkeratotic papules and nodules on her proximal lower extremities, upper extremities, and dorsal hands. She has a history of renal failure with 7 years of hemodialysis. The patient was placed on topical tretinoin cream 0.05% and has had near complete clearance of these lesions within 6 weeks. The acquired perforating disorders overlap clinically and histologically. The terminology has evolved too, using Kyrle's disease, perforating disease of chronic renal/liver failure and/or diabetes, perforating folliculitis, etc. These may represent the same disease along a spectrum. Perforating collagenosis is separate, with different demographics and often a history of trauma. This case is best classified as perforating folliculitis as the biopsy was classic for this entity. It shows a distorted follicle with an overlying funnel-shaped transepidermal channel.
A close-up view demonstrates this central keratotic plug with a rim of hypopigmentation.