Diagnosis: Keratoacanthoma vs. Prickle-Cell Epithelioma. Presented by Dr. Earle W. Brauer A 50-year-old white man presented a mass on the nose that was taken to be a keratoacanthoma on clinical grounds alone. Observation was decided upon. After several weeks of observation, no change occurring, the patient insisted upon intervention. A specimen was removed for histopathologic review, and the rest of the lesion was thoroughly electrodesiccated and curetted. The histologic interpretation confirmed the clinical impression of keratoacanthoma. The operative wound healed uneventfully. Three months later a firm, fleshcolored mass, then measuring 6 mm. in diameter, developed. Over the next 2 weeks further increase in size occurred. At a tumor board evaluation, the majority of members suspected the lesion was a prickle-cell epithelioma. The presenter and Dr. Arthur Hyman held to the diagnosis of keratoacanthoma and continued observation was bravely advised by them. In the subsequent 10 weeks the lesion disappeared spontaneously,