LAUSR

Keratoacanthoma centrifugum marginatum (KCM) is a rare variant of keratoacanthoma (KA), characterized by progressive annular plaques with central healing and peripheral extension. We report a case of multiple KCM in a young boy and review the published literature. A 5-year-old boy presented with a 3-year history of multiple, itchy, raised lesions, distributed predominantly over his legs. There was no family history of similar skin lesions. The patient had no history of sebaceous neoplasms or any visceral cancer, and there was no family history of such neoplasms. Physical examination revealed multiple annular plaques, 30–150 mm in size, on the legs, back, forearm and neck. The annular lesions had a white atrophic centre and peripheral keratotic papules with central plugging (Fig. 1a). Histological examination of a biopsy obtained from one of the papules showed a cup-shaped, keratin-filled crater with acanthosis and mild epithelial atypia (Fig. 2a). Apoptotic and dyskeratotic cells were noted. There was hyalinization and a dense lymphoplasmacytic infiltrate in the upper dermis (Fig. 2b). Based on these features, a diagnosis of multiple KCM was made. Mutational analysis of transforming growth factor (TGF)-b1 could not be performed because of lack of diagnostic facilities. The child was treated with oral isotretinoin 0.5 mg/kg per day, which resulted in healing of most of the lesions, leaving white atrophic scars (Fig. 1b). However, occasional new lesions continued to develop. At 10 months, the majority of the lesions had healed, at which point isotretinoin was stopped because of concerns of skeletal hyperostosis. Following this, there was recurrence of skin lesions. Oral methotrexate was started at a dose of 0.3 mg/kg/week, which resulted in the disease stabilizing. Unlike solitary KA, multiple KAs are rare tumours and can occur sporadically or as a part of familial