Pheochromocytoma and Paraganglioma

Paragangliomas (PGLs) are rare vascular, neuroendocrine tumors of paraganglia. They can occur sporadically or hereditary due to germ-line mutations in one of the more than 20 susceptibility genes. PGLs derive from either sympathetic tissue in adrenal (pheochromocytomas or PCCs) and extraadrenal locations (together called PPGLs) or parasympathetic tissue of the head and neck (HNPGLs). Since HNPGLs are usually benign and most tumors grow slowly, a wait-and-scan policy is often advised. However, their location in the close proximity to nerves and vasculature can result in considerable morbidity due to compression or infiltration of the adjacent structures. The main treatment modalities for HNPGL are surgery and radiotherapy. The majority of PPGLs produce catecholamines, with hypertension as most common feature. To detect these tumors, plasma-free metanephrines and/or 24 h-excretion of urinary fractionated metanephrines can be measured. Once a biochemical diagnosis of PPGLs has been established, the source of catecholamine excess is subsequently localized by anatomical (computed tomography and/or magnetic resonance imaging) and functional imaging studies (123I-MIBG-scintigraphy, positron emission tomography with radiolabeled DOTATE or FDG). The treatment of choice for PPGLs is surgical resection after adequate pretreatment with α-blockade, if necessary followed by β-blockade and volume expansion. Although most HNPGL are benign, up to 50% of PPGLs is malignant, depending on genetic background. Genetic testing can be of great importance for patients and their relatives because it gives the opportunity for early diagnosis through periodical imaging studies in the affected individual and family members. Early detection of a familial PGL allows early detection of potentially malignant PGLs and early surgical treatment, reducing the complication rate of this operation.