Background. Hereditary paraganglioma-pheochromocytoma syndrome is characterized by paragangliomas (tumors that arise from neuroendocrine tissues symmetrically distributed along the paravertebral axis from the base of the skull to the pelvis) and by pheochromocytomas (paragangliomas that are confined to the adrenal medulla). Sympathetic paragangliomas hypersecrete catecholamines and are located in the lower mediastinum, abdomen, and pelvis.
