[The clinical and pathological characters of malignant neoplasms arising from endometriosis].

Eight cases of malignant tumors arising from endometriosis were reported; the ovary was the primary site in 7, whereas extragonadal site (rectum) in 1. The histologic classification was as follows: endometrioid carcinoma in 1. Clear cell carcinoma in 2, mixed clear cell carcinoma and endometrioid carcinoma in 2, mixed papillary cystadenocarcinoma in 1 and serous tumor of borderline malignancy in 1. The histologic pattern arising from endometriosis of the rectal wall was endometrioid adenocarcinoma with benign endometriosis contiguous to it. It was found that the ectopic endometrial tissue may undergo malignant change when they were under stimulation by some factors. One of which may be intrinsic or extrinsic estrogen, which may be related to the high incidence rate in this age group. Laparotomy should be done for assessing malignant change when ovarian mass was greater than 10 cm or grew rapidly. Five year survival rate will be expected to improved with postoperative progestin or irradiation. Preventive measures were also suggested.