Keratoacanthoma is a benign tumor that shows spontaneous regression but often resembles well-differentiated squamous cell carcinoma histopathologically. Like squamous cell carcinoma, keratoacanthoma may show cellular atypia, mitosis, horn pearls, and focally infiltrative growth. In the present case, the initial microscopic section did not show a keratotic plug, and the first diagnosis was squamous cell carcinoma. However, additional sections cut from deeper in the tissue block revealed the central crater. Considering this architecture and the clinical course, the pathologic diagnosis was revised to keratoacanthoma. Specifically, features of rapid growth and a central crater are essential to diagnosis of keratoacanthoma.