Novel germline SDHD mutation: diagnosis and implications to the patient

A 54-year-old man presented with hypertensive crisis. He was found to have bilateral pheochromocytomas and left paraaortic sympathetic paraganglioma. Although he had no family history of paragangliomas or pheochromocytomas, he had been diagnosed with bilateral head and neck paragangliomas 10 years prior. The patient had symptoms of catecholamine excess exacerbated by vanilla ice-cream consumption. Biochemical testing revealed elevated plasma-free metanephrines and chromogranin A levels. Computed tomography showed bilateral carotid body tumors and four reteroperitoneal masses (two in the right adrenal, one in the left adrenal and one in the left paraaortic area). Metaiodobenzylguanidine-SPECT scans showed functional tumors in both the adrenal gland and left paraaortic area. Fluorine 18-fluorodeoxyglucose positron emission tomography did not show any visceral or skeletal metastasis. We carried out gene mutation analysis for succinate dehydrogenase complex subunit B, and succinate dehydrogenase complex subunit D. The patient was diagnosed with hereditary paraganglioma syndrome type 1 with a previously unreported subunit D mutation in exon 3 (c.198G > A, p.W66X). He was treated with phenoxybenzamine at 10 mg/day and with metoprolol at 12.5 mg/day. His blood pressures as well as symptoms of catecholamine excess were controlled. He then underwent bilateral adrenalectomy and reteroperitoneal dissection. His blood pressure normalized and he discontinued antihypertensive medications after surgery. He is currently on replacement therapy with hydrocortisone and fludrocortisone.