Primary renal carcinoid tumor: A rare cystic renal neoplasm

We present the case of a 21-year-old man with an incidentally detected cystic renal mass. A well-defined, solid mass measuring approximately 8 cm x 6 cm with a cystic component was identified in the left kidney by abdominal multidetector computed tomography (CT) and ultrasonography. The mass was well-enhanced on the corticomedullary CT phase and washout of enhancement occurred on the nephrographic phase. The mass contained peripheral wall and septal calcifications in the cystic component. The lesion was resected and diagnosed as a primary renal carcinoid tumor. Primary carcinoid tumors of the kidney are extremely rare. This case is notable because of the rarity of this neoplasm and its unique radiologic and pathologic findings. A review of previously reported cases in the literature is also presented.