Renal cell carcinoma metastatic to the ovary or fallopian tube: a clinicopathological study of 9 cases.

Renal cell carcinoma (RCC), the most common type of kidney cancer in adult, rarely metastasizes to the ovary or fallopian tube, and most cases published in the literature were case reports. Herein, we describe the clinicopathological features of 9 cases of RCC metastatic to the ovary (n = 8) or the fallopian tube (n = 1). The patients' age at the onset of primary renal tumor was available in 8 patients, ranging from 37 to 73 years (mean, 51 years; median, 50 years). Ovarian metastasis was detected prior to or concurrently with the primary renal tumors in 3 patients, and after the diagnosis of renal tumors in 6 patients. The histotypes of the RCCs were clear cell (n = 7), chromophobe (n = 1), and unclassified (n = 1). Immunohistochemical stainings were performed on the sections containing metastatic tumors in 4 cases. Interestingly, pagetoid intraepithelial spread in the tubal mucosa was observed in the case of RCC metastatic to the fallopian tube. Among the 8 patients with follow-up data, 5 died of disease and 3 were alive with disease, with a follow-up period ranging from 3.7 months to 17 years (mean, 77 months; median, 53 months) after the diagnosis of primary kidney tumors. Diagnostically, metastatic RCC may mimic primary ovarian tumors clinically, morphologically, or immunophenotypically. Pathologists should also keep in mind that both ovarian and kidney tumors express PAX8 and PAX2, the markers commonly used to diagnose metastatic RCC. In addition, chromophobe RCC only rarely metastasizes, but it can be a diagnostic challenge when it metastasizes to the ovary.