A case is presented in which a keratoacanthoma, treated with methotrexate and tetracycline with subsequent resolution, developed a basal cell carcinoma in the keratoacanthoma scar. After surgical removal of the tumor and skin grafting, a squamous cell carcinoma that was invasive into the nasal cartilage appeared at the site.
Burge KM, Winkelmann R. KeratoacanthomaAssociation With Basal and Squamous Cell Carcinoma. Arch Dermatol. 1969;100(3):306-311. doi:10.1001/archderm.1969.01610270048011