This 38-year-old African-American man developed pruritic erythematous papules on his arms and buttocks. In addition, he has chronic renal failure. Perforating folliculitis is one of the acquired perforating disorders. There is clinical and histologic overlap with Kyrle disease and the perforating disorder of renal failure and/or diabetes. This patient's clinical history of renal failure is common and therefore may be difficult to categorize. The follicular-based nature of his condition would favor perforating folliculitis, but the others cannot be excluded.
Histologic sections of skin show a central keratin-filled channel, traversing the epidermis. Not completely evident in this section, but the channel corresponds to a follicular unit. It is filled with abundant keratin and basophilic granular material. At its base, there is a perforation into the underlying dermis with an associated mixed inflammatory infiltrate. The surrounding epidermis is acanthotic.