A case of keratoacanthoma arising in the lower lip

Keratoacanthoma (KA) is a benign lesion of epithelial hyperplasia originating from the surface epithelium. This lesion is frequently mistaken for squamous-cell carcinoma because of its similar clinical and microscopic characteristics. The lesion tends to occur in exposed areas. A case of KA arising in the lower lip of a 70-year-old man is presented.On November 22, 1995, a 70-year-old man presented with white marks and a dry feeling of his lower lip; however, there was no pain. Clinically, the lower lip appeared to have a leukoplakia-like lesion, which measured 35×15 mm and was well defined.The patient had suffered from HCV hepatitis, for which he had received treatment 5 years ago. In May 1994, he felt slight pain in his lower lip and applied Azunol ointment to it.On November 28, 1995, examination of a biopsy specimen revealed keratoacanthoma with a slightly dysplastic epithelium. The patient was followed up to May 1996; the lesion continued to grow as an exophytic mass and measured 30×15×1Omm. On May 24, 1996, as spontaneous regression appeared improbable, he was given vitamin A. Thereafter, the lesion regressed considerably, but the patient could not bear the disgusting odor of tumor necrosis.On October 17, 1996, the patient underwent resection of the lower lip tumor along with an adequate margin of normal tissue. As of the present, there has been no evidence of tumor recurrence.