Dermoscopic findings in a case of reactive perforating collagenosis.

Reactive perforating collagenosis (RPC) is the most common type of acquired perforating dermatoses (APD), [1] and is characterized by umbilicated papules and plaques with central crusted ulceration. Pruritus is the most common symptom of RPC, and the lesions are most commonly found on the extensor surfaces of the extremities. This entity is histopathologically characterized by invagination of the epidermis and transepidermal elimination of collagen bundles. The pathogenesis of RPC is still somewhat unclear, but it has been reported that trauma resulting from scratching may induce damage to the epidermis or dermal collagen [1,2]. Moreover, RPC is commonly found in association with chronic renal failure and diabetes mellitus.Dermoscopy is a noninvasive technique that has been used in the diagnosis of APD [3], especially for perforating folliculitis (PF). However, to our knowledge, the dermoscopic features of RPC have not been previously described in the literature. Here, we report the dermoscopic features and their histological correlations in RPC as a means to improve the diagnosis of this condition.