[A case of carcinoid tumor arising from a horseshoe kidney]

Carcinoid tumor of the kidney is an extremely rare neoplasm. We report a case of primary carcinoid tumor arising from a horseshoe kidney in a 31-year-old man. An abdominal bulky mass was found at a local hospital and he was referred to our hospital for examination and treatment. From the results of computed tomography, magnetic resonance imaging and angiography, we suspected renal tumor arising from a horseshoe kidney and performed left partial nephrectomy with isthmectomy. Pathological findings of hematoxylin eosin staining revealed tumor cells proliferating in a cord-like and ribbon-like structure and the tumor cells stained strongly for chromogranin A, grimelius and neuron specific enolase. According to these findings, we diagnosed carcinoid tumor arising from a horseshoe kidney.