Primary carcinoid of the renal pelvis.

We report a case of a surgically resected carcinoid of the renal pelvis diagnosed as papillary transitional cell carcinoma by light microscopy. Immunocytochemistry studies identified three immunoreactive products: cytokeratin, S-100 protein, and neuron-specific enolase. Ultrastructurally, dense core granules were seen. The histogenesis of renal pelvis carcinoid has not been clarified. This is the first documented case of a renal pelvis carcinoid.