DURING the past decade keratoacanthoma has become established as a distinct and important clinical entity, likely to be encountered by any physician accustomed to treating skin tumors. Although the lesion was described by Hutchinson as long ago as 1888,1 it remained all but unknown in the English literature until its reintroduction by the papers of Smith2,3 and Dunn3 in 1934. Formerly the disease was known by a variety of terms including crateriform ulcer, selfhealing squamous cell carcinoma, and molluscum sebaceum. In 1936, Freudenthal devised the now generally accepted name, keratoacanthoma.4-6 Widespread American interest in keratoacanthoma began with the report of Levy et al in 1954.7 Few articles on keratoacanthoma have appeared in the surgical literature. Keratoacanthoma is a lesion closely resembling well-differentiated squamous cell carcinoma in gross and microscopic appearance. In clinical behavior, however, the two diseases are quite different because keratoacanthoma, after a spurt