Large infiltrating renal transitional cell carcinomas: CT and ultrasound features.

A series of nine patients with large infiltrating renal transitional cell carcinomas is presented. These large tumors are rare but important in the differential diagnosis of renal masses. The average tumor size was 8.5 cm. In six patients the tumor involved almost the entire kidney. Seven masses were centrally located but two were peripheral. With CT the masses exhibited low attenuation relative to the normal or opposite renal parenchyma. Four masses exhibited necrosis. Lymphadenopathy, venous invasion, calcification, and spontaneous hemorrhage were all seen in this series. The major differential diagnostic possibility was renal cell carcinoma but lymphoma and metastatic disease were included. The diagnosis was confirmed in six patients by fine needle aspiration biopsy because of the presence of metastatic disease or the possibility of lymphoma. In the remaining three patients the diagnosis was made at surgery. The recognition that a large infiltrating renal mass may represent a transitional cell neoplasm is important in the eventual surgical management, and accurate preoperative diagnosis is stressed.