Primary renal carcinoid tumor: A radiologic review

Carcinoid tumor is the classic famous anonym of neuroendocrine neoplasms. Primary renal carcinoid tumors are extremely rare, first described by Resnick and colleagues in 1966, with fewer than a total of 100 cases reported in the literature. Thus, given the paucity of cases, the clinical and histological behavior is not well understood, impairing the ability to predict prognosis. Computed tomography and (occasionally) octreotide studies are used in the diagnosis and followup of these rare entites. A review of 85 cases in the literature shows that no distinctive imaging features differentiate them from other primary renal masses. The lesions tend to demonstrate a hypodense appearance and do not usually enhance in the arterial phases, but can occasionally calcify. Octreotide scans do not seem to help in the diagnosis; however, they are more commonly used in the postoperative followup. In addition, we report a new case of primary renal carcinoid in a horseshoe kidney.