A paraganglioma is a rare tumor that grows from clusters of specialized nerve-related cells called paraganglia, which are scattered along major blood vessels and nerves from the skull base to the pelvis. These tumors can appear almost anywhere in the body, but the two most common sites are the adrenal glands (where the tumor is traditionally called a pheochromocytoma) and the head and neck region. What makes paragangliomas especially interesting, and sometimes frustrating to manage, is that up to half of all cases trace back to an inherited gene mutation, a proportion far higher than in most cancers.
Where Paragangliomas Grow and Why Location Matters
Paraganglia are tiny organs left over from embryonic development. They come in two functional flavors. Sympathetic paraganglia sit alongside the spine and in the adrenal glands; they can produce catecholamines, the fight-or-flight hormones like adrenaline and noradrenaline. Parasympathetic paraganglia cluster in the head and neck, particularly near the carotid artery bifurcation, the jugular foramen, the middle ear, and along the vagus nerve. Tumors arising from sympathetic tissue tend to cause hormonal symptoms, while head and neck paragangliomas are usually non-secreting and instead announce themselves as a painless neck mass or through cranial nerve problems like hearing loss, hoarseness, or difficulty swallowing.1PubMed Central. Paragangliomas/Pheochromocytomas: clinically oriented genetic testing
Head and neck paragangliomas are highly vascular tumors, which means they have a rich blood supply and tend to light up dramatically on imaging.2PubMed. Morphological and functional imaging of neck paragangliomas This vascularity is part of why biopsy is almost never done before surgery; sticking a needle into one of these tumors risks serious bleeding. The location also dictates the urgency of treatment. A small, slow-growing carotid body tumor in an elderly patient might be safely watched with imaging. A large catecholamine-secreting abdominal paraganglioma in a young person is typically a surgical emergency waiting to happen, because uncontrolled hormone surges can trigger dangerous blood pressure crises.
The Genetic Roots
Few tumor types are as deeply intertwined with genetics as paragangliomas. About half of all cases are linked to inherited mutations, most commonly in the genes encoding the four subunits of succinate dehydrogenase, collectively called SDHx.3Genetics in Medicine. Efficacy of clinical screening of individuals with germline SDHx pathogenic variants Succinate dehydrogenase is an enzyme that sits at the crossroads of two fundamental cellular energy processes. When one of its subunit genes (SDHA, SDHB, SDHC, or SDHD) carries an inactivating mutation, the enzyme breaks down and succinate accumulates inside the cell. That buildup tricks the cell into behaving as though it is starved of oxygen, even when oxygen is plentiful, a state researchers call pseudohypoxia.4PubMed Central. Pseudohypoxia in paraganglioma and pheochromocytoma is associated with an immunosuppressive phenotype
Pseudohypoxia activates a cascade of pro-growth signals, including a transcription factor called HIF-2α, which ramps up blood vessel formation and cell survival. Roughly 40% of all paragangliomas and pheochromocytomas carry a germline mutation in either an SDH subunit gene or the von Hippel-Lindau (VHL) gene, and these tumors show a strong pseudohypoxic signature.5PubMed Central. Metabolic implications of hypoxia and pseudohypoxia in pheochromocytoma and paraganglioma The inheritance pattern for SDHB, SDHC, and SDHD mutations is autosomal dominant, meaning a single copy of the faulty gene is enough to raise risk. SDHD has an additional quirk: it is maternally imprinted, so you only develop tumors if you inherit the mutation from your father.6PubMed Central. SDH-related Pheochromocytoma and paraganglioma
Beyond SDHx mutations, three well-known cancer predisposition syndromes also carry paraganglioma risk: multiple endocrine neoplasia type 2 (driven by mutations in the RET gene), von Hippel-Lindau disease (VHL gene), and neurofibromatosis type 1 (NF1 gene).7PubMed Central. Pheochromocytoma and paraganglioma syndromes: genetics and management update Patients with VHL disease tend to have the highest noradrenaline secretion, which can lead to sustained high blood pressure, while those with neurofibromatosis type 1 and MEN2 show a more adrenaline-heavy hormonal profile.8PubMed. Perioperative outcomes of syndromic paraganglioma and pheochromocytoma resection in patients with von Hippel-Lindau disease, multiple endocrine neoplasia type 2, or neurofibromatosis type 1 These hormonal differences affect which symptoms a patient experiences and how aggressively their blood pressure needs to be controlled before surgery.
How Paragangliomas Are Detected
If a paraganglioma produces catecholamines, the classic presentation is episodes of severe headache, sweating, rapid heartbeat, and a sudden spike in blood pressure. Some patients describe an overwhelming sense of dread or anxiety during these episodes. The diagnosis rests on measuring catecholamine metabolites in the blood or urine. Plasma free metanephrines are the most sensitive screening test, picking up about 98% of hormone-secreting tumors.9Endocrine Reviews. Biochemical Assessment of Pheochromocytoma and Paraganglioma Adding a measurement of methoxytyramine, a dopamine metabolite, improves detection for head and neck paragangliomas specifically, which often produce only dopamine and would otherwise be biochemically silent.10European Journal of Endocrinology. Plasma methoxytyramine: clinical utility with metanephrines for diagnosis of pheochromocytoma and paraganglioma
Once biochemistry raises the flag, imaging pins down the tumor’s location. CT with contrast or MR angiography are excellent first-line tools for head and neck tumors.11PubMed Central. Multimodality imaging of paragangliomas of the head and neck For the whole-body picture, especially when metastatic disease is suspected, nuclear medicine scans have become indispensable. Gallium-68 DOTATATE PET/CT, which targets somatostatin receptors on the tumor surface, has emerged as the standout performer, detecting disease at close to 98% of sites in some studies and outperforming both conventional CT/MRI and older nuclear scans.12PubMed Central. PET/CT comparing (68)Ga-DOTATATE and other radiopharmaceuticals and in comparison with CT/MRI for the localization of sporadic metastatic pheochromocytoma and paraganglioma In one head-to-head comparison, DOTATATE PET/CT found all lesions detected by other modalities plus additional ones that had been missed.13PubMed Central. 68Ga-DOTATATE PET/CT in the Localization of Head and Neck Paragangliomas Compared with Other Functional Imaging Modalities and CT/MRI
Metastatic Risk and the SDHB Question
One of the most consequential distinctions in paraganglioma care is whether the tumor has the potential to spread. The 2022 WHO classification considers all paragangliomas to have some metastatic potential, which means the old binary of “benign versus malignant” has been retired in favor of risk stratification. Among the genetic subtypes, SDHB mutations carry the highest metastatic risk by a significant margin. A recent meta-analysis found that the rate of metastatic disease in SDHB carriers was roughly 2.3-fold higher than in patients with other cluster 1 genetic variants.14The Journal of Clinical Endocrinology & Metabolism. Metastatic Disease in Phaeochromocytomas and Paragangliomas in Various Genotypes—A Systematic Review and Meta-analysis
Factors that further raise concern include a tumor larger than 5 cm, an extra-adrenal location, elevated plasma methoxytyramine, and high proliferation markers on pathology.15Nature Reviews Endocrinology. Management of phaeochromocytoma and paraganglioma in patients with germline SDHB pathogenic variants: an international expert Consensus statement That said, predicting which individual tumor will metastasize remains frustratingly imprecise. Researchers have noted that common markers like Ki-67 are less useful for paragangliomas on a patient-by-patient basis than they are for other neuroendocrine tumors. This uncertainty is a major reason why lifelong follow-up is recommended for anyone with a known genetic predisposition.
Surgery and Preoperative Preparation
Surgical removal remains the only curative treatment for localized paragangliomas. For catecholamine-secreting tumors, the weeks before surgery are a critical window. The traditional approach involves prescribing alpha-adrenergic blockers (drugs that counteract the effects of excess adrenaline and noradrenaline) for at least two weeks before the operation, followed by beta-blockers if needed, along with liberal fluid and salt intake to expand blood volume.16PubMed Central. Current perioperative management of pheochromocytomas The idea is to calm the cardiovascular system before surgeons start manipulating a tumor that could dump a massive dose of catecholamines into the bloodstream.
Interestingly, recent evidence has questioned whether alpha-blockade actually improves surgical outcomes. A meta-analysis comparing preoperative alpha-blockade to no blockade found that the drugs did not ensure more stable blood pressure during surgery or better outcomes afterward.17PubMed Central. Preoperative α-blockade versus no blockade for pheochromocytoma–paraganglioma patients undergoing surgery: a systematic review and updated meta-analysis This does not mean centers are abandoning the practice; most endocrine surgery teams still use alpha-blockade as a safety net, especially for large or highly secretory tumors. But the finding has opened the door to more tailored approaches, particularly in centers with experienced anesthesia teams who can handle intraoperative blood pressure swings in real time.
Radiation for Head and Neck Tumors
Not every paraganglioma needs to be cut out. Head and neck paragangliomas are often slow-growing, and surgery near the carotid artery, jugular vein, and cranial nerves carries real risks of nerve damage. Radiation therapy, whether delivered as conventional fractionated treatments or as focused stereotactic radiosurgery, has become a well-established alternative for controlling these tumors. A retrospective analysis with a median follow-up of eight years reported a 100% local control rate with radiation, and no patient experienced significant toxicity.18PubMed Central. Efficacy and Safety of Radiotherapy in Head and Neck Paragangliomas: A Retrospective 23-Year Analysis A meta-analysis of stereotactic radiosurgery reported local control of about 94%, with no meaningful difference between the various radiosurgery platforms.19PubMed. Stereotactic radiosurgery for head and neck paragangliomas: a systematic review and meta-analysis
The goal of radiation in this context is not to make the tumor disappear but to stop it from growing. Most treated tumors stay the same size or shrink slowly over years. For patients whose tumors are in surgically treacherous spots, or who are elderly or have bilateral tumors, radiation offers disease control with a much lower chance of complications like vocal cord paralysis or stroke.
Treating Metastatic Disease
When paragangliomas spread, treatment becomes more complex and less standardized. No single approach dominates, and care often involves cycling through several options depending on response, tumor genetics, and how the disease behaves over time.
Peptide receptor radionuclide therapy (PRRT) with lutetium-177-DOTATATE uses the same somatostatin receptors targeted by diagnostic DOTATATE scans, but this time with a radioactive payload attached. Early data suggest meaningful disease control. One retrospective series found that 80% of treated patients achieved stable disease or better, and no serious long-term kidney or bone marrow damage was observed.20PubMed Central. 177Lu-DOTATATE therapy in metastatic/inoperable pheochromocytoma-paraganglioma A separate single-center analysis likewise concluded that PRRT was effective and appeared to improve patients’ quality of life.21PubMed Central. 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) in metastatic phaeochromocytomas and paragangliomas (mPPGL): a single centre retrospective analysis of experience at an ENETS Centre of Excellence
Conventional chemotherapy with the CVD regimen (cyclophosphamide, vincristine, and dacarbazine) and the targeted agent sunitinib are other options. Sunitinib has shown the ability to shrink tumors, reduce metabolic activity on PET scans, and stabilize disease, though progression-free survival in one study was modest at about four months.22PubMed Central. Treatment with sunitinib for patients with progressive metastatic pheochromocytomas and sympathetic paragangliomas A multicenter retrospective study comparing first-line options found disease control rates in the range of 75% to 100% across CVD, PRRT, MIBG therapy, and sunitinib, though the duration of disease stabilization varied widely.23European Journal of Endocrinology. Responses to systemic therapy in metastatic pheochromocytoma/paraganglioma: a retrospective multicenter cohort study
Belzutifan and the Promise of HIF-2α Inhibition
The most exciting recent development in paraganglioma treatment targets the pseudohypoxia pathway directly. Belzutifan is a selective inhibitor of HIF-2α, the protein that drives much of the tumor biology in SDHx- and VHL-mutated paragangliomas. Its first reported use was striking: a patient with Pacak-Zhuang syndrome, a rare condition caused by a somatic mutation in EPAS1, had multiple paragangliomas, severe high blood pressure, and polycythemia. Treatment with belzutifan led to sustained tumor shrinkage and resolution of all three problems.24PubMed Central. Belzutifan, a Potent HIF2α Inhibitor, in the Pacak-Zhuang Syndrome
Broader testing followed. The LITESPARK-015 phase 2 trial enrolled patients with advanced or metastatic pheochromocytoma and paraganglioma and reported a disease control rate of 85% and a tumor response rate of 26%.25PubMed. Belzutifan, A Hypoxia-Inducible Factor 2-Alpha Inhibitor, for Patients with Advanced Pheochromocytoma and Paraganglioma For a tumor type that has long lacked effective drug options, these numbers are meaningful. Belzutifan is the first drug to directly address the molecular driver behind most aggressive paragangliomas, and further studies are evaluating its role in earlier lines of therapy.26PubMed. Belzutifan for Advanced Pheochromocytoma or Paraganglioma
The Immune Landscape and Why Immunotherapy Has Been Slow
Given the success of checkpoint immunotherapy in other cancers, researchers have naturally looked at whether paragangliomas could respond to similar approaches. So far, the picture is discouraging for most subtypes. Genomic and immune profiling of metastatic tumors has revealed a broadly immunosuppressive microenvironment: lower levels of active immune cells, fewer CD8-positive T cells (the main tumor-killing immune cells), and higher numbers of M2-type macrophages, which actually help tumors evade immune destruction.27Nature Communications. Genomic and immune landscape of metastatic pheochromocytoma and paraganglioma One intriguing exception is a subgroup of tumors driven by MAML3 fusions, which do express the PD-L1 checkpoint protein. These patients could theoretically benefit from immune checkpoint inhibitors, but the subgroup is small and clinical trial data are limited.
Paragangliomas in Children
Pediatric cases account for a small minority of all paragangliomas, but they differ from adult cases in several important ways. Children are more likely to have extra-adrenal tumors, multifocal disease, and metastases at diagnosis. The reason is straightforward: pediatric paragangliomas are almost always driven by a germline mutation, most often in VHL or one of the SDHx genes, with SDHB and SDHA variants conferring the highest metastatic risk.28PubMed Central. Pediatric Metastatic Pheochromocytoma and Paraganglioma: Clinical Presentation and Diagnosis, Genetics, and Therapeutic Approaches Genetic predisposition means these tumors start developing earlier, giving them more time to grow and spread before they cause symptoms noticeable enough for a child to be evaluated. This is why expert guidelines recommend starting tumor screening as early as age 6 to 10 for children who carry an SDHB mutation.29Nature Reviews Endocrinology. International consensus on initial screening and follow-up of asymptomatic SDHx mutation carriers
Lifelong Surveillance for Mutation Carriers
Discovering that you carry an SDHx mutation, even without a tumor diagnosis, changes your medical life permanently. International guidelines recommend annual blood tests measuring catecholamine metabolites and whole-body MRI every two years, starting five years before the youngest age at which a tumor appeared in the family.30PubMed. Genetic testing and surveillance guidelines in hereditary pheochromocytoma and paraganglioma For SDHD and SDHAF2 mutations, which show maternal imprinting, first-degree relatives and even second-degree relatives through the paternal line should be offered carrier testing.
The screening ages vary by gene. SDHB carriers start earliest (age 6 to 10) because of the higher metastatic potential. SDHA, SDHC, and SDHD carriers with paternal imprinting begin between 10 and 15.31Nature Reviews Endocrinology. International consensus on initial screening and follow-up of asymptomatic SDHx mutation carriers There is no agreed-upon age at which screening can safely stop. Some carriers develop their first tumor in their sixties, so the practical reality is that surveillance continues indefinitely.
The Psychological Toll of Living with Genetic Risk
The emotional weight of carrying an SDHx mutation is underappreciated. A study measuring quality of life found that mutation carriers without any diagnosed tumor still reported significantly lower perceived physical health compared to the general population. Nearly 15% of carriers and over 21% of patients with unresected head and neck paragangliomas reported clinically relevant anxiety, compared to about 6% in the general population.32PubMed. Quality of life in patients with pheochromocytoma and paraganglioma: influence of tumor type, genetics and surgical resection A separate study focused on the psychological impact of genetic testing itself found that almost 30% of tested individuals scored high on a measure of global suffering related to their test results, with affected mutation carriers showing lower quality of life and higher anxiety and depression than carriers who had not yet developed tumors.33PubMed. Pheochromocytoma and paraganglioma genetic testing: Psychological impact
These findings matter for clinical practice. When a genetic counselor delivers an SDHx result, the conversation should not be purely technical. Connecting patients with psychological support, peer communities, and clear explanations of what surveillance actually involves can reduce the uncertainty that fuels so much of the anxiety. The data suggest that the mental health burden is not about having cancer; it is about not knowing if or when cancer will arrive.
High Altitude and the Carotid Body Connection
An unusual piece of the paraganglioma puzzle comes from geography. People living at high altitudes have a higher incidence of carotid body paragangliomas. The carotid body is a tiny oxygen-sensing organ at the fork of the carotid artery in the neck. When someone lives in chronically low-oxygen conditions, the carotid body enlarges in response, a process called hyperplasia.34PubMed Central. High Altitude Head and Neck Paragangliomas: A First Sub‐Himalayan Experience In some individuals, that persistent growth stimulus tips over into tumor formation. The link between real hypoxia (thin mountain air) and pseudohypoxia (the metabolic trick played by SDH mutations) is not just a conceptual parallel. Researchers have found that some high-altitude paraganglioma patients also carry SDHB mutations, suggesting the two risk factors can converge in the same person.35Clinical Cancer Research. Mutation of SDHB is a Cause of Hypoxia-Related High-Altitude Paraganglioma This convergence reinforces why genetic testing is worthwhile even in populations where environmental risk factors seem to offer a sufficient explanation on their own.