Perniosis: clinical and histopathological analysis.

Perniosis are inflammatory cutaneous lesions, located on acral skin, which present in association with cold exposure. They can appear as an idiopathic dermatosis or with an underlying autoimmune disease. The use of cutaneous biopsy to distinguish between both types is controversial. We analyze the histological findings in 9 cases of idiopathic perniosis (IP) and compare them with those obtained from 11 cases of perniosis associated with an autoimmune disease (autoimmune perniosis). The most frequent histopathological features observed in cases of IP were a lymphocytic infiltrate with perivascular (8 cases, 89%) and perieccrine distribution (6 cases, 66%), dermal edema (5 cases, 55%), and necrotic keratinocytes (5 cases, 55%), whereas those found in perniosis associated with an autoimmune disease were lymphocytic infiltrate with perivascular distribution (11 cases, 100%) but without perieccrine distribution (3 cases, 27%), vacuolation of the basal layer (7 cases, 63%), and necrotic keratinocytes (5 cases, 45%). The only significant difference between both groups was the perieccrine distribution of the lymphocytic infiltrate in cases of IP, which, as mentioned in previous studies, could be considered a histopathological clue to differentiate both types of perniosis.