A case of renal cell carcinoma metastatic to the ovary: a case report and review of the literature

A 35-year-old woman complained of pain in the left hypochondrium. She was diagnosed as having a left renal carcinoma and treated with retro-approach radical nephrectomy without lymphadenectomy. The histology was renal cell carcinoma (RCC), papillary cell type 2, G3, expansive type, INFα, v(+), pT2N0M0, stage II. The Memorial Sloan-Kettering Cancer Center risk classification was favorable. Then, 18 months later, a multilocular cystic mass (15 × 10 cm) in the pelvis was found on abdominal CT and MRI. Although the ovarian tumor was highly suspicious of malignancy, differentiation between primary and metastatic ovarian tumor was not possible. Examination of the resected right ovarian tumor showed that it consisted of clear cell type (G2) that resembled components of the left RCC. When we resected the right ovarian tumor, we found some nodules on the peritoneum. There seemed to be new suspicious metastases. Immunohistochemistry revealed that only CD10 was positive; 34βE12, CA125, and CK7 were negative. These results indicated renal metastasis. The patient then underwent targeted therapy with sunitinib 50 mg/day for 28 days. One month later, a new metastasis was found in the left ovary and treated surgically. Soon thereafter, a brain metastasis was found and the patient underwent radiation therapy to the brain, but she died 21 months after the nephrectomy. Metastasis to the ovary from RCC is very rare, and only 20 cases have been reported. Its rarity may be related to the difficulty associated with the differential diagnosis of metastatic ovarian tumors from RCC and primary ovarian clear cell carcinoma. Careful histological and immunohistochemical analysis may help differentiate the two.