Endometrioid Endometrial Carcinoma With NKX3.1 Expression in a Transgender Man: A Case Report.

Endometrial cancer in transgender men is rare, and its histopathologic features remain unknown. A 30-yr-old transgender man with an intrauterine tumor, an ovarian mass, and a 2-yr history of testosterone use was referred to us for treatment. The presence of the tumors was confirmed via imaging, and the intrauterine tumor was identified as an endometrial endometrioid carcinoma via endometrial biopsy. The patient underwent hysterectomy, bilateral salpingo-oophorectomy, omentectomy, and lymph node dissection. Pathologic examination revealed grade 3 endometrioid endometrial carcinoma, and the synchronous endometrial and ovarian tumors were collectively characterized as primary endometrial carcinoma. Metastatic carcinomas were discovered in both ovaries and the omentum, pelvic peritoneum, and a para-aortic lymph node. On immunohistochemistry, the tumor cells diffusely expressed p53, retained expression of PTEN, ARID1A, PMS2, and MSH6, and focally expressed estrogen receptors, androgen receptors, and NKX3.1. NKX3.1 was also expressed in glandular structures within the exocervical squamous epithelium. Prostate-specific antigen and prostatic acid phosphatase were focally positive. In conclusion, we describe a transgender man with NKX3.1-expressing endometrioid endometrial carcinoma who provide valuable suggestions regarding the effects of testosterone on endometrial cancer and appropriate gynecological care for transgender men.