Clear cell renal cell carcinoma with syncytial giant cells: a case report and review of the literature.

Renal cell carcinoma with syncytial giant cells (SGCs) is rare; to our knowledge, there are only 3 cases reported in the English literature. We report on a case that, unlike previous reports, was associated with higher grade renal cell carcinoma and an aggressive behavior. A 63-year-old man with gross hematuria was found to have a large left renal mass and no evidence of metastasis. The nephrectomy specimen contained a 14.8-cm mass that was confined within the renal capsule. Microscopically, a 1.8-cm area of SGCs was noted in a background of clear cell renal cell carcinoma of Fuhrman nuclear grades 2 to 4. The SGCs had voluminous cytoplasm, multiple large nuclei with prominent nucleoli, and focal emperipolesis. Identical to the background mononuclear tumor cells, the SGCs were positive for AE1/AE3, vimentin, and epithelial membrane antigen and negative for CD68, beta-human chorionic gonadotropin, and mucin. Three months after surgery, the patient developed metastases in the liver, right kidney, and lungs.