Keratoacanthoma developing in sites of previous trauma: a report of two cases and review of the literature.

Keratoacanthoma is a common benign squamous neoplasm that only rarely progresses to metastatic carcinoma. The cause of keratoacanthoma is unclear; however, suspected causes include ultraviolet light, genetic factors, immunosuppression, chemical carcinogens, viruses, and trauma. Keratoacanthomas have been reported only rarely to arise in sites of previous trauma. We report 2 cases of keratoacanthomas arising shortly after episodes of cutaneous trauma and provide a review of the literature of similar cases previously reported. It is likely that an interaction exists between a variety of factors in the development of keratoacanthomas; however, it appears that a predilection exists for these lesions to arise in trauma sites.