Keratoacanthoma centrifugum marginatum after photodynamic therapy with good response to oral retinoids and topical 5-fluorouracil.

Keratoacanthoma centrifugum marginatum (KCM) is a rare variant of keratoacanthoma (KA), characterized by progressive peripheral growth, and usually devoid of deep invasion. Different systemic (oral retinoids) or topical treatments have been reported, but there is not a well-defined therapeutic protocol. We report the case of a KCM developing after photodynamic therapy (PDT) on the right leg of a 64-year-old woman. It was treated successfully with oral acitretin combined with topical 5-Fluorouracil + salicylic acid for 5 months. This is the first case of KCM developing after PDT and successfully treated with oral retinoid combined with topical treatment.