CT and MR imaging of multilocular acinar cell cystadenoma: comparison with branch duct intraductal papillary mucinous neoplasia (IPMNs).

OBJECTIVES: To describe CT and MR imaging findings of acinar cell cystadenoma (ACC) of the pancreas and to compare them with those of branch duct intraductal papillary mucinous neoplasia (BD-IPMN) to identify distinctive elements. METHODS: Five patients with ACC and the 20 consecutive patients with histologically proven BD-IPMN were retrospectively included. Clinical and biological information was collected and histological data reviewed. CT and MR findings were analysed blinded to pathological diagnosis in order to identify imaging diagnostic criteria of ACC. RESULTS: Patients with ACC were symptomatic in all but one case and were younger than those with BD-IPMN (p = 0.006). Four radiological criteria allowed for differentiating ACC from IPMN: five or more cysts, clustered peripheral small cysts, presence of cyst calcifications and absence of communication with the main pancreatic duct (p < 0.05). Presence of at least two or three of these imaging criteria had a strong diagnostic value for ACC with a sensitivity of 100% and 80% and a specificity of 85% and 100%, respectively. CONCLUSIONS: Preoperative differential diagnosis between ACC and BD-IPMN can be achieved using a combination of four CT and/or MR imaging criteria. Recognition of ACC patients could change patient management and lead to more conservative treatment. KEY POINTS: Four imaging findings are associated with acinar cell cystadenoma (ACC). Imaging could achieve differential diagnosis between ACC and BD-IPMN. Diagnosis on imaging would change patient management and avoid surgical resection.