[Tricholemmal keratosis and tricholemmal cancer]

Three cases of tricholemmal keratosis and two of tricholemmal carcinoma are reported. All patients were female and the age range was from 71 to 83 years. These rare tumors occur on the face and are obviously the result of long-standing actinic skin damage. Clinically, verrucous hyperkeratosis or cornu cutaneum (keratosis) are observed and in the case of tricholemmal carcinomas, ulcerated tumor nodules. Histologically pale, glycogen-rich polygonal cells with signs of tricholemmal keratinization without the presence of a granular cell layer are characteristic features. Tricholemmal keratoses exhibit no atypia or only a mild form; however, carcinoma in situ may occasionally develop. In contrast, tricholemmal carcinomas are characterized by increased pleomorphia, an increase in the rate of mitosis, and an invasive growth pattern. The prognosis is favourable.