Three histologically distinct cancers of the uterine corpus: A case report and review of the literature.

Collision tumors, which are characterized by the coexistence of two or more completely distinct and independent tumors in the uterine corpus, are very rare. A collision tumor is mainly composed of two distinct tumor types, epithelial and mesenchymal. To the best of our knowledge, there has only been a single case in which a choriocarcinoma with an endometrial carcinoma were coexistent but histologically distinct. We herein report the first case of a collision tumor in a 52-year-old woman, with a history of two pregnancies and two deliveries. The collision tumor was composed of three histologically distinct neoplasms in the uterine corpus, namely an endometrioid carcinoma, an undifferentiated carcinoma and a choriocarcinoma. The patient underwent hysterectomy, bilateral adnexectomy and pelvic lymph node dissection, followed by six cycles of adjuvant chemotherapy with paclitaxel/carboplatin due to the high risk of endometrial cancer, and an additional five cycles of chemotherapy with methotrexate, as the β-human chorionic gonadotropin level was beyond the normal range. Following adjuvant chemotherapy, the tumor markers were within normal limits and no relapses of the cancer have been observed during 1 year of follow-up. Diagnosing a collision tumor prior to surgery is difficult if the neoplasms are in close proximity, or if one of the tumors predominates. Careful pathological examination is crucial for accurately diagnosing the neoplasms in a collision tumor and ensuring appropriate management and a favorable prognosis.