[Keratoacanthoma. A variant of highly differentiated squamous cell carcinoma and its differential diagnosis].

Keratoacanthomas represent epithelial tumors which are characterized by a keratin-filled crater, rapid growth in the proliferation stage, and the potential for spontaneous regression. Histologically, keratoacanthomas display distinct features which must be differentiated from squamous cell carcinomas in the proliferation stage and fully developed tumors and in the regression stage the differential diagnosis of verruca vulgaris must also be considered.