Collecting duct carcinoma of the kidney: CT and pathologic correlation

Purpose: We characterized CT findings of collecting duct carcinoma of the kidney and correlated these with the histopathologic findings. Materials and methods: CT scans of 18 patients with pathologically proven collecting duct carcinoma of the kidney were retrospectively reviewed. We analyzed CT findings of collecting duct carcinoma and also correlated CT findings with the histopathologic findings. Results: The mean size of the tumors was 6.9 cm and all cases were solid. Seventeen (94%) tumors had a medullary location. Nine (69%) and 11 (85%) cases showed weak and heterogeneous enhancement, respectively. A cystic component (50%) was frequently seen within the tumors. Lymphadenopathy and metastasis were noted in 10 (56%) and 6 (33%) cases, respectively. Perinephric stranding and vascular invasion were present in 10 (56%) and 5 (28%) cases, respectively. In 17 (94%) of the 18 cases, involvement of the renal sinus was present. Infiltrative growth (67%) and preservation of the renal contour (61%) were more common than expansile growth (33%) and exophytic configuration (39%), respectively. These CT features were well correlated with the histopathologic findings. Conclusion: Medullary location, weak and heterogeneous enhancement, involvement of the renal sinus, infiltrative growth, preserved renal contour, and a cystic component are CT findings frequently seen in patients with collecting duct carcinoma of the kidney. CT findings are nevertheless nonspecific and do not allow collecting duct carcinoma to be easily differentiated from the other subtypes of renal cell carcinoma. However, when CT demonstrates a renal tumor with these findings, collecting duct carcinoma can be considered in the differential diagnosis.