No abstract

The clinical and pathologic features of cutaneous metastasis were studied in 724 patients, with histopathologic confirmation of both the primary tumors and the secondary lesions in the skin. Cutaneous metastatic lesions from carcinoma of the lung and kidney were usually found in men, were often recognized before the primary tumor, and appeared in almost every area of the skin surface. Metastasis from carcinoma of the breast to the skin occurred almost exclusively in women, tended to be localized to the anterior chest wall, and was usually found after the primary tumor. Most cutaneous lesions metastasizing from squamous cell carcinoma of the oral cavity were found on the face or neck of men in whom there was previous histologic documentation of the primary tumor.

Comparison of 50 proliferating trichilemmal cysts with 50 "ordinary" trichilemmal cysts indicated that both types almost invariably occurred on the scalps of women, were diagnosed clinically as cysts, followed a benign course, and featured trichilemmal keratinization. A spectrum was observed from trichilemmal cyst with minimal hyperplasia, to full-blown proliferating trichilemmal cyst. Occasionally, patients had ordinary trichilemmal cysts on their scalps associated with a proliferating trichilemmal cyst. In addition to trichilemmal keratini-zation, which is characteristic of the follicular isthmus, proliferating trichilemmal cysts showed a wider range of differentiation, including features of the follicular infundibulum, the lower nonkeratinizing portion of the follicular outer root sheath, and sebaceous cells. Intense inflammatory infiltrate and cellular atypia, sometimes of significant proportions, were also seen in proliferating trichilemmal cysts. It is concluded that trauma and inflammation may induce a trichilemmal cyst to proliferate and show a broader spectrum of pilosebaceous differentiation and cellular atypia of pseudocarcinomatous proportions, while maintaining its benign biologic behavior. Cancer 481207-1214,1981. HERE IS A PECULIAR benign cutaneous growth that T usually resembles a cyst clinically, but is often histologically misinterpreted as squamous cell carcino-ma. Our purpose here is to analyze the clinical and his-tologic features of a large series of proliferating trichilemmal cysts. Evidence is presented on the pathogenetic relationship between proliferating and ordinary trichilemmal cysts. Emphasis is placed on the wide range of pilosebaceous differentiation and striking cellular dysplasia encountered in proliferating cysts, compared with the restricted pattern of ordinary trichilemmal cysts. Material and Methods Fifty proliferating trichilemmal cysts were collected during the past nine years. Minimal clinical data required for inclusion in this study were the sex and age of the patient and the anatomic site of the growth. Histologic sections were reviewed in all cases. For comparative purposes, 50 uncomplicated trichilemmal cysts were studied. Clinical Features Among the 50 patients with trichilemmal cysts, 84% were women; 90% of the lesions were on the scalp (Fig. l), two were on the back, and one each on the forehead (Fig. 2), wrist, and chest (Fig. 3). The age range was 27-83 (median 59) years. One patient was in the third, 2 in the fourth, 9 in the fifth, 14 in the sixth, 14 in the seventh, 6 in the eighth, and 4 in the ninth decade. The duration ranged from one-half to over 20 (median 2) years. Sometimes, a cystic lesion had been present for years, then slowly enlarged. In 94%, the clinical diagnosis was "sebaceous," pilar, trichilem-mal, or epidermoid cyst; in two patients it was squam-ous cell carcinoma and in one, dermatofibroma. For about 50% of the patients, there was intermittent discharge or inflammation; several growths were eroded or ulcerated. Occasionally there was' bleed...