The authors report a case of keratoacanthoma localized on the prolabium of the lower lip. They focus their attention on the difficulty of making a correct diagnosis and on the complexity of differential diagnosis with squamous cell carcinoma. After incisional biopsy of the lesion, treatment took the form of the complete excision of the neoplasm which is indispensable for a definitive diagnosis. The keratoacanthoma, although being an absolutely benign lesion, in fact requires complete exeresis in order to perform an histological examination of the entire neoplastic mass and thus definitively rule put the presence of squamous cell carcinoma. If correctly performed, the operation leaves very little scarring and satisfies the patient's esthetic and psychological expectations.