A 30-year-old woman presented with a 1-year history of a pruritic eruption on the extremities, characterized by several annular plaques. The patient had been treated unsuccessfully with medium-potency topical steroids. The lesions had an erythematous papular border with an atrophic center (width, 1-4 cm) (Fig. 1). No oral, genital, or nail lesions were observed. A skin biopsy from one of the plaques was performed. Histopathologic examination of the raised border showed hyperkeratosis of the stratum corneum, focal thickening of the granular layer, basal liquefaction degeneration of the epidermis, and a band-like subepidermal infiltration with numerous Civatte bodies. In the center of the lesion, the epidermis became thinner (Fig. 2). Elastic fibers were reduced or absent in the papillary dermis. The patient was treated with high-potency topical steroids for 2 months with clinical improvement.

Porokeratosis of Mibelli is a rare genodermatosis characterized by a disorder of keratinization. None of the currently available therapies is effective in all cases and this situation exposes the patient to multiple treatment cycles. We describe the successful use of topical imiquimod 5% cream in the management of porokeratosis of Mibelli of the axillae in a 12-year-old girl. Treatment with imiquimod was effective, probably due to the area of application, where large hydrated skin folds are found, which helps penetration of the drug on the stratum corneum.