一部脂腺への分化がみられた外毛根鞘癌

Abstract

A 90-year-old female had noticed a skin eruption on her left thigh about 4 years before. Because the eruption gradually increased in size and elevated with bleeding on its surface, she visited our clinic on January 17th, 1994. Four and 2cm in diameter, well-demarcated skin nodules were seen on the left thigh. Clinical diagnosis was squamous cell carcinoma. Total resection was performed 1cm apart from the margins of the lesion. Histologically, tumor nests, which were attached to the overlying epidermis, existed from the dermis to cutaneous tissue. The peripheral part of each tumor nest showed a palisading arrangement. In the inner layer of each tumor nest, so-called clear cells intermingled with large cells, the cytoplasm of which appeared as a delicate network. Some tumor cells had large and irregular shaped nuclei. Ultrastructurally, the peripheral cells of each tumor nest were connected to the basal lamina through hemi-desmosomes. Dilatation of rough or smooth endoplasmic reticula was observed in the cytoplasm. In the inner layer of tumor nests, some tumor cells contained lipid droplets which had a clear center. Immunohistochemical examination revealed that tumor cells reacted positively with HMFG-1, EMA, Ks19.1, LP34 and KL1. On the other hand, CEA, S-100, 34β B4 and 35β H11 were negative. HMFG-1 and Ks19.1 reacted to only sweat and sebaceous glands. We considered that there was no differentiation toward sweat glands in our case because CEA and S-100 showed negative reactions. From these findings, We diagnosed this case as trichilemmal carcinoma with partial differentiation of sebaceous gland.