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).