RENAL ONCOCYTOMA MIMICKING HEMORRHAGIC RENAL CYST

A case of oncocytoma, the radiological findings of which resembled a hemorrhagic renal cyst, is reported. Cyst fluid analysis demonstrated extremely high levels of carcinoembryonic antigen (CEA) and carbohydrate antigen 19–9 (CA19–9). Preoperatively the lesion was regarded a malignant cyst, and radical nephrectomy was performed. Pathological diagnosis was renal oncocytoma with cystic degeneration. Although cystic change occasionally has been mentioned in oncocytoma, a high level of CEA and CA 19–9 in the cyst fluid of the cystic oncocytoma have not been reported. We discuss the variant forms of oncocytoma and tumor markers in the cyst fluid.