Abstract
Paragangliomas (PGLs) are rare neuroendocrine tumors that arise from the extra-adrenal autonomic paraganglia, a diffuse neuroendocrine system dispersed from the skull base to the pelvic floor, derived from the embryonic neural crest cells [1-3]. Paragangliomas arising from the sympathetic ganglia of the thorax, abdomen and pelvis may be catecholamine secreting, and form 15%-20% of the PPGLs (pheochromocytomas and paragangliomas), whereas paragangliomas originating from the parasympathetic ganglia of the head and neck region (HNPGLs) are often nonsecretary.
While hypertension is present in the vast majority (95%) of patients with adrenal pheochromocytomas, the extraadrenal sympathetic PGLs of the thorax, abdomen and pelvis may not always present with hypertension. For example, dopamine secreting PPGLs usually present without hypertension [4].
There are distinct differences between the adrenal pheochromocytomas and the extraadrenal PGLs in the clinical presentation, genetic characteristics, malignant potentials, management algorithms, and prognostic factors [1,5]. We outline an evidence-based review of the epidemiology, pathophysiology, genetics, clinical characteristics, diagnostic algorithms, and therapeutic aspects of PGLs in this chapter.