Cytological features of carcinoma of the collecting ducts of Bellini in voided urine cytology.

Carcinoma of the collecting ducts of Bellini (CCDB) is a rare histological type of renal cell carcinoma. This article describes the cytological features of CCDB in voided urine, confirmed on the basis of the histopathology and immunohistochemistry. The CCDB cells occurred singly in loose aggregates and in small clusters, occasionally in a rosette-like structure. There were various types of cancer cells, including round to oval, spindle, and tadpole-like cells. The nuclei usually showed coarse chromatin, inconspicuous nucleoli, and lacy to vacuolated cytoplasm. CCDB of the kidney is a rare cytodiagnostic challenge in voided urine cytology alone. When the cytological diagnosis is considered, it is necessary to perform immunocytochemistry and correlate the clinical history and imaging studies.