Giant keratoacanthomas.

A patient with multiple keratoacanthomas association with a well-differentiated squamous cell carcinoma is presented. Incomplete excision of a keratoacanthoma deprives the pathologist of his main criteria in differentiating this lesion from a squamous cell carcinoma. Wide excision appears to be the treatment of choice. Multiple keratoacanthomas can be associated with squamous cell carcinomas, which initially look identical. Persistence with conservative treatment in a growing lesion can fail to deal with an invasive squamous cell carcinoma which will require disfiguring or mutilating operations to cure. Squamous cell carcinoma does develop in keratoacanthomas, but metastases are rare.