Perforating collagenosis.

A 55-year-old man presented with a three-week history of pruritic, erythematous papules with hyperkeratotic dells on the dorsum of the left hand, which was preceded by swelling, redness and itching. Histopathologic examination showed an acanthotic epidermis with a central invagination filled with a plug composed of parakeratotic debris, collagen, and inflammatory cells. These findings are consistent with acquired reactive perforating collagenosis, which is most frequently reported in patients with pruritus and underlying diabetes mellitus or chronic renal insufficiency. Topical and oral retinoids and topical and intralesional glucocorticoids have been reported to be effective in some patients in case series.