Three extra-uterine tumors, unassociated with endometriosis, had light microscopic features of endometrial stromatosis (low-grade endometrial stromal sarcoma). Two tumors occurred in the retroperitoneum and one adjacent to the vagina. Distinctive features identifying these neoplasmas as ectopic growths of endometrial stroma included prominent vessels with concentric whorls of tumor cells, foam cells, eosinophilic hyaline globules, bland cytologic features, and rare mitoses. The ultrastructure of one of the tumors was typical of endometrial stroma. Infiltrative margins and analogy with endometrial stromatosis make late recurrence likely unless excision margins are adequate. The postulated histogenesis of the tumors is mesothelial and mesenchymal cells of pelvis and retroperitoneum. Pre-existing endometriosis of ectopic ovary is possible but unnecessary. Recognition of the distinctive pattern of these slow-growing tumors should prevent confusion with more aggressive sarcomas.
ASJC Scopus subject areas
- Pathology and Forensic Medicine