Acinar cell carcinoma of the pancreas - Clinical and computed tomography manifestations

Purpose: Acinar cell carcinoma (ACC) is a subtype of pancreatic neoplasm sufficiently rare that its imaging has not been fully analyzed. The purpose of this article is to present the computed tomography (CT) appearance of ACC of the pancreas. Methods: Clinical data and CT studies of 10 patients (7 male and 3 female) with pathologically proven ACC of the pancreas were reviewed. Among the CT features emphasized were the presence of a well-defined enhancing capsule, foci of internal calcification, intra-tumoral hemorrhage, presence of a central hypodense area, and degree of contrast enhancement. Results: The presenting symptoms of ACC of the pancreas were nonspecific. An elevated serum level of alpha-fetoprotein, carcinoembryonic acid, and CA 19-9 was noted in 2 (20%), 1 (10%), and 3 (30%) patients, respectively. The tumor locations were in the uncinate process in 4 (40%), in the head and neck in 2 (20%), in the body in 1 (10%), and in the tail in 3 (30%) patients. The average tumor size was 7.2 cm (range: 3.3-18 cm). A well-defined enhancing capsule, internal foci of calcification, and intratumoral hemorrhage appeared in 6 (60%), 5 (50%), and 0 tumors, respectively. Eight (80%) tumors had a central hypodense area; of these, 4 (40%) tumors exhibited a hypodense area greater than 50% of the tumor. During dynamic CT in 8 patients, 6 tumors showed early arterial (EA) enhancement and persisted into the portal venous (PV) phase, whereas the other 2 tumors revealed enhancement in the EA phase and washout in PV phase. Conclusion: Acinar cell carcinoma typically presents as a sizable pancreatic mass with a well-defined enhancing capsule and internal calcifications. Significant central hypodensity is frequently present. Recognition of these features can provide clues to the CT diagnosis of ACC.