Renal hilus paraganglioma: a case report and brief review.

Paraganglioma is a rare tumour that originates from any paraganglia. Among extra-adrenal paraganglioma, renal hilus is a rare location. The authors report a case of a 43-year-old female who was admitted for evaluation of a renal mass detected incidentally by ultrasound imaging. Suspecting malignancy, the patient underwent radical nephrectomy. Upon macroscopic examination, the lesion was located into the renal hilus. Histological study revealed a neoplasm constituted of nests of monomorphic cuboidal cells with basophilic granular cytoplasm and round to oval nuclei. Necrosis was absent. The proliferative index (Mib-1) was very low (< 5%). Immunohistochemical examination revealed reactivity for neuron specific enolase (NSE), chromogranin A and synaptophysin. The final diagnosis was renal hilus paraganglioma. The paper shows the difficulty in diagnostic approaches to paraganglioma in this atypical site.