Metastasis of Clear Cell Renal Cell Carcinoma to Uterine Leiomyoma: First Case Report and Review of Literature.

Metastasis of clear cell renal cell carcinoma (clear cell RCC) to the gynecologic tract is infrequent, and involvement of the uterus is extremely rare. A review of the literature identified a total of 12 reported examples with metastasis to the uterine serosa (1), endometrium (5), cervix (5) and only one with metastasis to the myometrium. This report represents the first case of tumor-to-tumor metastasis involving a clear cell RCC with metastasis to a uterine leiomyoma. The patient was a 50-year-old woman status post-radical nephrectomy for newly diagnosed unilateral clear cell RCC (stage pT3a) with negative margins, who subsequently underwent a total abdominal hysterectomy and bilateral salpingo-oophorectomy for the incidental finding of multiple uterine masses measuring up to 14.5 cm suggestive of fibroid on pelvic ultrasound. The pathologic exam of the specimen was consistent with metastatic clear cell RCC (1.2 cm) to uterine leiomyoma, confirmed with keratin, vimentin, CD10, CA9, and PAX8 immunohistochemistry. The patient's postoperative course was uneventful, and no new lesions were identified at follow-up during the past 6 months.