Background: Keratoacanthoma centrifugum marginatum is a rare variety of keratoacanthoma, usually presented and classified as solitary keratoacanthoma. Reported cases of multiple keratoacanthoma centrifugum marginatum are exceptional in the literature.
Observations: A 21-year-old man presented for evaluation of erythematous papules and plaques on both legs that had had a peripheral growth over the past year. Clinical and histologic examination showed typical features of keratoacanthoma centrifugum marginatum. Owing to the multiplicity and size of the lesions, treatment with oral isotretinoin was started. It was ineffective. Subsequent treatment with methotrexate combined with oral prednisone led to the regression of all lesions.
Conclusions: The exceptional case of a man with multiple keratoacanthoma centrifugum marginatum is reported. Treatment with methotrexate combined with oral prednisone was effective. This case illustrates how some variants of keratoacanthomas do not really fit into the current classification and how complex the treatment of these tumors is.