[A case of collecting duct carcinoma (Bellini duct carcinoma) producing carcinoembryonic antigen].

We report a case of collecting duct carcinoma (Bellini duct carcinoma) producing carcinoembryonic antigen (CEA). A 61-year-old man visited our hospital because of a left renal mass detected by ultrasonography in an other hospital. Computed tomography showed a low density tumor measuring about 3 cm in the left kidney. Angiography demonstrated a hypovascular tumor. The serum level of CEA was increased to 20 ng/ml. (normal < 7 ng/ml). Left radical nephrectomy was performed. Histological examination revealed collecting duct carcinoma with papillary growth (T1aN1M0). Cancer cells showed a positive immunohistochemical staining for CEA. Under a diagnosis of CEA-producing collecting duct carcinoma of the left kidney, the patient underwent systemic chemotherapy (M-VAC). The serum level of CEA decreased to the normal level after the nephrectomy, but six months postoperatively, metastatic bone tumor at the left pelvic bone was revealed on the plain film and at the same time, the CEA level was increased again.