Abstract: Objective To retrospectively analyze the clinical data of clinically silent pheochromocytoma in 29 cases in order to improve its diagnosis and treatment. Methods 29 patients were diagnosed pathologically as adrenal pheochromocytoma from May 2010 to May 2013, who were considered clinically silent and operated in Peking Union Medical College Hospital. We summarized the aspects include patient age, tumor location and maximal diameter, operation method, change of intraoperative blood pressure(BP), urinary catecholamine and the nuclear medicine examinations. Results Each of the 29 patients had a normal BP, and the results of urinary catecholamine were normal or elevated lightly. The maximal diameter of tumors were 1.5~14cm. 1 case was located in both side, while 13 cases in the right and 15 cases in the left. 25 were operated laparoscopically, and the other 4 underwent open operations. BP was stable in all the 23 cases who were given cardula, while 2 of 6 cases who were not given cardula had hypertensive crisis. 11/23 cases had false negative results in somatostatin receptor imaging, while 1/11 cases had a false negative result in 131IMIBG imaging. Conclusions Urinary catecholamine and somatostatin receptor imaging are not sensitive to clinically silent pheochromocytoma. 131IMIBG imaging is necessary to the cases who are highly suspicious in CT imaging. Surgical treatment should be carried out on the basis of correct drug preparation once the correct diagnosis is made.

Key words: clinically silent, pheochromocytoma