[Extra-adrenal pheochromocytoma: update of the most controversial features. Apropos of two cases].

Pheochromocytomas are uncommon neuroendocrine tumors. They are usually symptomatic and sporadic and are generally located in the adrenal medulla. We present two cases of extra-adrenal nonfunctional pheochromocytomas located in the retroperitoneum. The tumors were apparently benign and sporadic and were not associated with other neoplasms or hereditary diseases. Ultrasonography, computed axial tomography and magnetic resonance imaging were performed before complete excision of the tumors using open abdominal surgery. Several immunohistochemical techniques were performed to reach the definitive diagnosis. After 8 and 14 months of follow-up, there is no evidence of recurrence or other syndromes. As a consequence of these two cases, we performed a review of the literature on the topic, focussing on the most controversial areas.