Hereditary pheochromocytoma and paraganglioma (SDHx, VHL, RET, NF1, MAX and TMEM127)

Pheochromocytomas (adrenal) and paragangliomas (sympathetic chain, head and neck) have the strongest hereditary basis of any tumour type: germline mutations are found in 30 to 40 percent of patients, in the succinate dehydrogenase genes (SDHB, SDHD, SDHC, SDHA and SDHAF2), VHL, RET (MEN2), NF1, MAX, TMEM127, FH and others, and the Endocrine Society guideline recommends that all patients be offered testing. The genes fall into two clusters that shape the tumour: cluster 1 (SDHx, VHL, FH, EPAS1) tumours are pseudohypoxic, noradrenergic or non-secreting, often extra-adrenal and multiple, and express somatostatin receptors strongly; cluster 2 (RET, NF1, MAX, TMEM127) tumours are kinase-driven, adrenergic and usually adrenal. SDHB mutations carry the highest risk of metastasis, SDHD (paternally inherited) causes multiple head and neck paragangliomas, VHL and MEN2 cause bilateral pheochromocytomas alongside their other tumours, and SDHx carriers are also at risk of gastrointestinal stromal tumours, renal cell carcinoma and pituitary adenomas.

Management differs from sporadic disease at every step. Diagnosis rests on plasma or urinary metanephrines and, for non-secreting head and neck tumours, imaging; SDHB immunohistochemistry on the tumour flags an SDHx mutation, and 68Ga-DOTATATE PET is the preferred whole-body scan for cluster 1 disease because of its somatostatin receptor expression. Surgery follows alpha-blockade, and in VHL and MEN2 a cortical-sparing adrenalectomy is preferred to avoid lifelong steroid dependence after bilateral tumours; head and neck paragangliomas, which rarely secrete and grow slowly, are often watched or irradiated rather than resected because surgery risks the cranial nerves. Carriers enter lifelong surveillance with annual metanephrines and periodic whole-body MRI from childhood in SDHB and SDHD families, and cascade testing is offered to relatives. For carriers who develop advanced disease, the HIF-2 alpha inhibitor belzutifan, approved for VHL-associated tumours in 2021 and for advanced pheochromocytoma and paraganglioma in 2025, exploits the pseudohypoxia pathway directly, and radioligand therapy with lutetium-177 dotatate suits the somatostatin-receptor-rich cluster 1 tumours. The genetics also guide prognosis: metastatic risk, multiplicity and the chance of a second primary all follow the gene.