Abstract: Objective To explore clinical and genetic manifestation of pheochromocytoma patients with RET gene mutation. Methods Clinical data, laboratory examination results and RET gene mutations of 23 pheochromocytoma patients with RET mutation treated in Peking Union Medical College Hospital from 2013 to 2019 were retrospectively analyzed. Results The diagnosis age of pheochromocytoma in 23 patients was 32±10 years. In 22 patients with multiple endocrine neoplasia (MEN) 2A, mutations were clustered in exon 16 (18 cases), especially in codon 634 (16 cases), followed by exon 10 and 14, and one patient with MEN2B had M918T in exon 16. Among the 23 patients, 9 had paroxysmal hypertension, 5 had sustained hypertension, 3 were normotensive, and 6 had episodic palpitations but their blood pressures were not measured during the attacks. 24 h urinary catecholamine excretion was as following: norepinephrine (NE): 65.8 (36.9,235.9) μg/24 h, Epinephrine (E): 5.4 (2.8, 37.2) μg/24 h and Dopamine (DA): 277 (198, 297) μg/24 h. 15 patients had abnormally increased NE, E or DA, while 8 patients had normal catecholamine excretion. The median diameter of the tumors was 4 (3, 6) cm. Fifteen patients had bilateral pheochromocytoma and 17 had medullary thyroid carcinoma. Conclusions Pheochromocytoma patients with RET mutation are consistent with those reported in western countries in terms of age at diagnosis, tumor size and mutation profile. Most patients have paroxysmal hypertension or normal pressure, and some of them have normal urinary catecholamine excretion, which are potential risk factors of missed diagnosis.

Key words: pheochromocytoma, RET gene, multiple endocrine neoplasiatype 2