EXTRAUTERINE LOW-GRADE ENDOMETRIAL STROMAL SARCOMA - REPORT OF 3 CASES

Three cases of rare low-grade endometrial stromal sarcoma of the extra uterine tissue are presented. Each one occurred in the ovary, pelvic a nd abdominal cavities. Two were associated with endometriosis. Histolo gically, the tumors were characterized by an infiltrative and diffuse proliferation of uniform round or oval cells, abundant small vessels, low mitotic activity, the presence of foam cells and vascular invasion . Immunohistochemically, all tumors expressed vimentin, muscle markers (desmin, muscle-specific actin and alpha-smooth muscle actin) and pro gesterone receptors. Two tumors were diploid and one was aneuploid by flow cytometry. All patients were well with no evidence of disease 16- 39 months after surgery. It is suggested that this neoplasm may arise with or without endometriosis under hormonal influence. This rare vari ant of Mullerian tumors should not be confused with adenosarcoma and s oft tissue tumors, such as smooth muscle tumors and solitary fibrous t umor.