Accessory spleen: a potential cause of misdiagnosis at EUS.

BACKGROUND

Accessory spleen is a common congenital anomaly. There are currently no endoscopic ultrasound (EUS) criteria for the diagnosis or differentiation of this benign splenic anomaly from pathologic disorders including neoplasms. The purpose of this study was to characterize EUS features and develop criteria for the diagnosis of accessory spleen.

METHODS

Ten patients undergoing EUS were found to have a possible pancreatic tail or perisplenic mass later confirmed by CT to be either an accessory spleen or a prominent lobule of the spleen. EUS criteria assessed included size, shape, location, echo texture, echo density and border demarcation.

RESULTS

Ten patients (mean age 58 years) were evaluated. Indications for EUS were evaluation of pancreaticobiliary disease in 9 patients and a gastric submucosal mass in 1 patient. Eight patients had an accessory spleen and 2 had a lobulated spleen. The mean diameter of these lesions as seen on EUS was 2.70 x 3.12 cm. Nine were round and 1 was oval. Because all were located inferolateral to the pancreatic tail and medial to the spleen, 5 of 10 were initially thought to be pancreatic masses. All of these lesions had a sharp and regular outer margin and homogeneous echo texture, 4 were hypoechoic and 6 hyperechoic. There were no specific EUS features identified that differentiated splenic lobulations from accessory spleen.

CONCLUSIONS

Accessory spleen and splenic lobulation can be misinterpreted as neoplasm by EUS. Although homogeneous, they can be hyperechoic or hypoechoic. Their sharp and regular outer margin and anatomic location may help to avoid misdiagnosis. Furthermore, computed tomography may be helpful in confirming their presence.