Keratoacanthoma centrifugum marginatum: a diagnostic and therapeutic challenge.

A keratoacanthoma centrifugum marginatum (KACM) may pose a diagnostic and therapeutic challenge. Clinically and histologically, it may resemble mycobacterial or deep fungal infection or halogenoderma. Therapy can be challenging because the lesion can expand to a great size. We report on a patient with multiple lesions of KACM. The diagnostic difficulty and the therapeutic failure of imiquimod, intralesional methotrexate (MTX), and isotretinoin, as well as the therapeutic success of 5-fluorouracil (5-FU) cream, are discussed.