Non-Neoplastic Masses of the Pancreas.

Benign non-neoplastic solid lesions of the pancreas are comprised of several separate entities, with their diagnostic identification best performed in correlation with the radiographic and clinical features. These include all of the pancreatitides, intrapancreatic spleen, and a few other rare entities. Preoperative imaging may suggest the correct diagnosis, but occasionally the preoperative imaging findings may be misleading because they overlap with those of pancreatic neoplasms. Masses associated with typical pancreatitides are rarely sampled due to their distinct clinical picture and relative frequency; however, the uncommon variants of pancreatitis may also present as mass lesions mimicking malignancy. Herein, we will discuss the cytopathologic findings of several solid pancreatic lesions, including acute pancreatitis, chronic pancreatitis, autoimmune pancreatitis, paraduodenal or groove pancreatitis, and other mass lesions, such as intrapancreatic accessory spleen and abscess. The key cytological features, ancillary studies, and differential diagnoses will also be discussed.