[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Hereditary paraganglioma and pheochromocytoma (SDH) [Conditions](https://durgical.com/en/conditions/) · [Metabolism (biochemistry)](https://durgical.com/en/conditions/) # Hereditary paraganglioma and pheochromocytoma (SDH) Some families inherit changes in succinate dehydrogenase that cause tumours in the neck and the adrenal glands. Updated 2026-10-31 ## Structures involved Tap one to see what it is and open it in 3D. - [Carotid bifurcation](https://durgical.com/en/anatomy/carotid-bifurcation/) - [Right adrenal gland](https://durgical.com/en/anatomy/suprarenal-gland-abdomen/) - [Left adrenal gland](https://durgical.com/en/anatomy/suprarenal-gland/) - [Vagus nerve](https://durgical.com/en/anatomy/vagus-nerve/) - [Common carotid artery](https://durgical.com/en/anatomy/right-common-carotid-artery/) - [Kidneys](https://durgical.com/en/anatomy/kidney/) ## In biochemistry - [Krebs cycle: Step 6 · Succinate dehydrogenase (complex II)](https://durgical.com/en/biochemistry/pathways/krebs-cycle/#paso-6) - [Malate–aspartate shuttle: Step 2 · 2-Oxoglutarate/malate carrier (OGC, SLC25A11)](https://durgical.com/en/biochemistry/pathways/malate-aspartate-shuttle/#paso-2) - [Succinate dehydrogenase (complex II)](https://durgical.com/en/biochemistry/enzymes/succinate-dehydrogenase/) - [Catecholamines: synthesis and breakdown](https://durgical.com/en/biochemistry/topics/catecholamines-synthesis-and-breakdown/) - [FAD (flavin adenine dinucleotide)](https://durgical.com/en/biochemistry/molecules/fad/) - [Oncogenes and tumour suppressor genes](https://durgical.com/en/biochemistry/topics/oncogenes-and-tumour-suppressor-genes/) - [Warburg effect (aerobic glycolysis in cancer)](https://durgical.com/en/biochemistry/topics/warburg-effect/) ## In embryology - [Adrenal gland: cortex from mesoderm, medulla from neural crest](https://durgical.com/en/embryology/adrenal-gland-cortex-from-mesoderm-medulla-from-neural-crest/) ## Why it happens - [Tumour angiogenesis](https://durgical.com/en/general-pathology/tumour-angiogenesis/) - [Hereditary cancer syndromes: the table to know](https://durgical.com/en/general-pathology/hereditary-cancer-syndromes-the-table-to-know/) ## What it is Tumours of the paraganglia (carotid body, [vagus nerve](https://durgical.com/en/anatomy/vagus-nerve/), sympathetic chain) and the adrenal medulla caused by germline variants in the succinate dehydrogenase genes (SDHA, SDHB, SDHC, SDHD, SDHAF2). ## Who gets it About one third of paragangliomas and pheochromocytomas are inherited. Carotid paraganglioma is more common in people living at high altitude, as in the Andes. ## Causes - A variant in an SDH gene inherited from one parent (autosomal dominant) - SDHD and SDHAF2: the tumour usually appears only if the variant comes from the father ## Risk factors - Relatives with paraganglioma or pheochromocytoma - Multiple tumours or a young age - Living at high altitude (carotid body) ## Pathophysiology Without succinate dehydrogenase, succinate builds up and inhibits the enzymes that break down hypoxia-inducible factor (HIF). The cell reacts as if short of oxygen: vessels and cells grow. That is why succinate is called an 'oncometabolite'. ## Symptoms and signs - A painless lump on the side of the neck - Episodes of headache, sweating and palpitations (if the tumour secretes catecholamines) - High blood pressure that is hard to control - Hoarseness, hearing loss or pulsatile tinnitus ([head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) tumours) ## Red flags - A hypertensive crisis, especially with anaesthesia or certain drugs - Bone pain or weight loss (metastasis, more with SDHB) ## Diagnosis **Clinical** Suspect inheritance with multiple, young, extra-adrenal tumours or affected relatives. **Tests** Plasma free or 24-hour urine metanephrines; genetic testing of the SDH genes; SDHB immunohistochemistry of the tumour. **Imaging** CT or MRI to locate; DOTATATE PET (somatostatin analogue) for multiple tumours and metastases. ## Treatment **Medical** Alpha and then beta blockade before operating on a catecholamine-secreting tumour **Surgical** Surgical removal of the tumour **Procedure** Radiotherapy or radionuclide therapy in selected cases **Follow-up** Lifelong surveillance with biochemistry and imaging for carriers ## Complications - Hypertensive crisis - Metastasis (mainly SDHB) - Cranial nerve injury from the tumour or the surgery ## Test yourself Think of the answer, then tap the question to see it. ## Why is succinate called an oncometabolite? When it builds up it blocks HIF breakdown, creating pseudohypoxia that favours tumours. ## Which SDH gene carries the highest risk of metastasis? SDHB. ## Which biochemical test comes first? Plasma free metanephrines or 24-hour urine metanephrines. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/conditions/hereditary-paraganglioma-and-pheochromocytoma/) ## Related conditions - [Arterial hypertension](https://durgical.com/en/conditions/arterial-hypertension/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Hereditary paraganglioma-pheochromocytoma: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/hereditary-paraganglioma-pheochromocytoma/) (MedlinePlus, US National Library of Medicine, 2026); [SDHB gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/sdhb/) (MedlinePlus, US National Library of Medicine, 2026). 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