REVIEW OF THE LITERATURE PRIOR to 1917, keratoacanthomata were regarded as cancer of the skin. Lassar1 reported three cases of epithelioma in elderly patients that were cured by oral potassium arsenite solution. One of these also received subcutaneous injections of the arsenical solution. The clinical descriptions of these patients fit keratoacanthoma. Gougert* began reporting this disease as verrucome in 1917. Subsequently case reports † were numerous in 1929. The clinicians, unable to dismiss extragenital primary syphilis from their minds even after negative dark-field and serologic examinations, "cured" several verrucomes with intravenous neoarsphenamine. Additional reports ‡ from the continent appeared with the title of verrucome or vegetating sebaceous cyst. MacCormac and Scarff8 reported 10 keratoacanthomata in 1936 as molluscum sebaceum. The salient feature of the tumor was a rapid proliferation over a four to six weeks' period. In no case was there more than