ADENOMATOID TUMOR OF THE UTERUS

Abstract

A case of adenomatoid tumor of the uterus was reported. The patient, 48year-old woman, had a total hysterectomy for hypermenorrhea. The uterus wighed 530g and had multiple leiomyomas and two adenomatoid tumors. The adenomatoid tumors were located on the serosal surface of uterine fundus and of right anterolateral region respectively. They were both soybean-sized, multilocular cystic nodules. Microscopically, the tumor was composed of multiple channels or tubules lined by low cuboidal cells and of solid cords of epithelium-like cells. Vacuolation of the neoplastic cells was frequently observed. The cells lining the channels often had ragged luminal boundaries, suggesting brush borders. Mitotic figures were not seen. The tumor was not encapsulated, and extension of the neoplastic channels into the subjacent leiomyoma was observed at the margin of the tumor. By transmittion electron microscopy, the cells lining the channels were separated from the fibrous stroma by a single basement membrane. The tumor cells were rich in intracytoplasmic fibrillar structures, resembling tonofilaments. Numerous microvilli and occasional cilium were seen at the free luminal border of the cells. Each cell was connected by junctional complex and interdigitations of plasma membrane with the adjacent cell. Scanning electron microscopic examination disclosed crowded microvilli on the luminal surface of the tumor cell. Occasionally, swellings of the tip of the microvilli were observed. The light and electron microscopic observations presented here suggest the mesothelial nature of the neoplastic cells and give further support to the concept of a mesothelial origin of the adenomatoid tumor.