OBJECTIVEThe purpose of this study was to assess the imaging characteristics of abdominal pheochromocytoma in multiphasic spiral CT scanning, and to determine whether these image characteristics can aid in differentiating pheochromocytoma from other types of tumors or not.

METHODSThe image data of dynamic enhanced CT of 79 pathologically confirmed pheochromocytomas in 70 patients were retrospectively reviewed.

RESULTSAmong the 70 patients, there were 41 patients with endocrine symptoms related to pheochromocytoma, 15 had a latent pheochromocytoma and the remaining 14 cases presented with a non-functioning pheochromocytoma. There were totally 79 tumors in 70 patients, with a single lesion in 63 cases, while multiple lesions in the other 7. Sixty cases had a tumor located in the adrenal gland, while 8 in retroperitoneal space, and 2 cases had both intraadrenal and ectopic lesions simultaneously. Sixty patients had a benign pheochromocytoma, the other 10 had a malignant one or relapse after operation. The average size of the tumor was 5.8 cm (range, 2 approximately 15 cm in the longest diameter). Seventy-seven pheochromocytomas had a well defined boundary except two big ones with a unclear margin, which were finally proven to be malignant. Homogeneous enhancement was found in 6 lesions with a diameter

CONCLUSIONApproximately half of the abdominal pheochromocytomas are lack of endocrine symptoms related with their tumors. However, they may display some typical CT characteristics, such as that a small lesion is often homogeneous but hypervascular, a larger tumor may present hemorrhage, necrosis, and cystic change with rich or moderate blood supply. However, when a small tumor has moderate blood supply, it should be differentiated with an adrenal adenoma; when a big one has moderate blood supply, it should be differentiated with other malignant tumors. Furthermore, a part of malignant pheochromocytomas is really difficult to be differentiated from some benign lesions by spiral CT images alone.