A case of papillary renal cell carcinoma suggestive of Bellini duct origin.

A case of Bellini duct carcinoma is reported. A left renal tumor was detected by abdominal computerized tomography in a 76-year-old male, although he had no symptoms, such as hematuria, weight loss or flank pain. Radical nephrectomy was performed under the diagnosis of renal cell carcinoma in the left kidney. Macroscopic examination of the resected kidney revealed a tumor 2.0 cm in diameter, with a yellow-brown cut surface, located in the renal medulla. Histological examinations showed malignant tumor cells with eosinophilic cytoplasm with a papillary growth pattern. Immunohistostaining examinations using Lectin and two kinds of monoclonal antibodies demonstrated no significant staining with soybean agglutinin, peanut agglutinin, Dolichos biflorus agglutinin, Lotus tetragonolobus agglutinin or cytokeratin, and negative staining with Tamm-Horsfall protein. Although the results of immunohistostaining did not provide support, both macroscopic and microscopic findings strongly suggested that this tumor originated from Bellini duct epithelium (Bellini duct carcinoma). The patient is alive with no evidence of disease 1 year after surgery. Bellini duct carcinoma is a rare malignant condition and the prognosis is usually poor. Differential diagnosis from other renal or pelvic tumors is difficult and long-term careful follow-up is necessary.