ABSTRACT
Pheochromocytoma is a neuroendocrine tumor, embryologically derived from the neural crest and located principally in the abdomen. The anatomical distribution conforms to that of the sympatho-adrenal system with predominant origin from the adrenal medulla in approximately 90% of cases. Most of the abdominal extra-adrenal tumors are clustered around the adrenals and the remaining small fraction originates from sympathetic neurons along the para-aortic, iliac, and pelvic regions. Extra-abdominal tumors, mainly in the mediastinum and rarely in the neck, comprise approximately 2% of all pheochromocytomas (1).
