Pheochromocytomas are tumors originating from chromophobic tissue of neuroectodermal layer and mainly secrete catecholamines. Paragangliomas are classified into parasympathetic paragangliomas (including chemoreceptor tumors and carotid body tumors) and sympathetic paragangliomas (including retroperitoneal, pelvic and mediastinal paragangliomas) according to whether the tumors are from sympathetic or parasympathetic nerves. Some patients may suffer from severe cardiac, cerebral and renal damage due to long-term hypertension or sudden onset of severe hypertension leading to life-threatening crisis, but if timely and early diagnosis and treatment can be obtained, it is a curable secondary hypertensive disease. 1.What is pheochromocytoma? Pheochromocytoma is mainly a tumor originating from chromophores in the adrenal medulla, which can synthesize, store and catabolize catecholamines, and cause corresponding symptoms due to the release of the latter, while the traditional concept of extra-adrenal or ectopic pheochromocytoma can also be called paraganglioma. 2.What causes pheochromocytoma? The cause of pheochromocytoma is unknown and may be related to genetics. Recent studies have shown that about 30% have a family genetic background and the causative genes have been identified: VonHippel-Lindau disease (VHL disease, VHL gene mutation), multiple endocrine neoplasia type-1 (MEN-1, MEN1 gene mutation), multiple endocrine neoplasia type-2 (MEN-2, RET gene mutation), familial pheochromocytoma-pheochromocytoma syndrome ( SDHD, SDHB or SDHC gene mutations), neurofibromatosis type 1 (NF-1, NF-1 gene mutation). The rate of sporadic pheochromocytoma/pheochromocytoma gene mutations is approximately 24% in adults and up to 36% in children. The incidence of pheochromocytoma is 70% to 80% in MEN-2, about 10% in VHL disease, and about 3% to 5% in NF-1. 3.What are the clinical manifestations of pheochromocytoma? Hypertension is the most common clinical symptom, the incidence is about 80%-90%. 50%-60% is persistent, 40%-50% is episodic, 10%-50% can have postural hypotension, 5% can have normal blood pressure. It may be accompanied by the typical “triad” of headache, palpitation and excessive sweating, the incidence of which is more than 50%. The incidence of elevated blood glucose is about 40%. Some patients may present with cardiomyopathy, hypercalcemia, hematuria, diabetes mellitus, Cushing’s syndrome, intestinal obstruction, or even loss of vision; familial pheochromocytoma/pheochromocytoma can be characterized by clinical signs and symptoms of related syndromes: MEN-2 (medullary thyroid carcinoma, hyperparathyroidism, multiple mucosal neuroma), VHL disease (retinal and central nervous system) angioblastoma, renal cyst or renal cell carcinoma, pancreatic cyst or tumor, epididymal cystadenoma), NF-1 (multiple neurofibromas of the skin, chromatophores, iris “Lisser’s nodes”), familial pheochromocytoma-pheochromocytoma syndrome (parasympathetic paraganglioma of the head and neck, pheochromocytoma, sympathetic paraganglioma ), etc. About 15% may be associated with an abdominal mass. Rarely, the condition presents as an emergency: e.g. hypertensive crisis, shock, acute heart failure, pulmonary edema, myocardial infarction, severe cardiac arrhythmia, acute renal insufficiency, hyperthermia, etc. The incidence of pheochromocytoma in adrenal incidentalomas is about 5%. About 8% of patients are asymptomatic, mostly in familial cases or cystic pheochromocytomas with large tumors. 4.What parts of the body other than the adrenal gland can pheochromocytoma occur in? Pheochromocytoma mainly originates from the adrenal medulla, and about 9% to 24% originate from outside the adrenal glands. Most pheochromocytomas are unilateral, but hereditary cases are often bilateral and multiple, for example, about 50% to 80% of MEN-2 related cases are bilateral. About 95% of non-adrenal pheochromocytomas are located in the abdomen and pelvis, with the most common sites being the parietal aorta, near the renal hilum, and the inferior vena cava; followed by the pelvis, with pheochromocytomas of the bladder accounting for 0.5% of bladder tumors and 10% of pheochromocytomas; and then the head and neck and thoracic mediastinum. 15% to 24% can be multiple.