Intermittent postmenopausal vaginal bleeding as an indicator of vaginal metastasis from occult renal cell carcinoma with rhabdoid differentiation: a case report

The vagina is an exceptionally rare site for metastatic cancer. This case is reported due to its novelty, highlighting how vaginal metastasis can be the initial presentation of an occult renal carcinoma, particularly a highly aggressive variant with rhabdoid differentiation. A 58-year-old postmenopausal Han Chinese woman from Guangdong Province, China, presented with intermittent vaginal bleeding. Examination revealed a pedunculated vaginal mass. Pathological and immunohistochemical analysis (positive for PAX8, CAIX, CD10; negative for CK7) confirmed metastatic renal cell carcinoma. Subsequent imaging identified a primary left renal mass with venous tumor thrombi. The patient underwent cytoreductive radical nephrectomy and thrombectomy. Final pathology confirmed clear cell renal cell carcinoma, WHO/ISUP grade 4, with rhabdoid differentiation. This case underscores that a solitary vaginal mass may be a metastasis from an occult malignancy. It highlights the critical importance of considering a metastatic origin in the differential diagnosis, which necessitates a thorough investigation for a primary tumor, as the management and prognosis differ significantly from those of primary gynecological cancer.