Keratoacanthoma centrifugum marginatum associated with mechanical trauma: Response to acitretin-A case report and review of the literature.

Keratoacanthoma centrifugum marginatum (KCM) is a very rare variant of keratoacanthoma, characterized with progressive centrifugal growth, central healing, and atrophy. Due to its rarity and lack of distinctive histopathological features, KCM often raises diagnostic and therapeutic challenge. We present a case of a 76-year-old Caucasian woman with a single large tumor on her right shin that responded to oral retinoids. The patient presented history of local trauma. The tumor developed over the course of 20 months from a scar. To the best of our knowledge, this is the fifth case of KCM associated with mechanical trauma as a possible triggering factor.