Revised 12 June 2013

The pancreas is comprised predominantly of exocrine cells (acini and ductal cells) and endocrine cells (islets of Langerhans).

The exocrine component gives rise to adenocarcinomata, defined based on line of differentiation (ductal or acinar) , with usual ductal adenocarcinoma (PDAC) being the most common lesion; up to 85% of all malignant neoplasms of the pancreas. Less common subtypes include adenosquamous carcinomas, squamous cell carcinomas, and giant cell carcinomas.

The ampulla of Vater usually refers to confluence of distal common bile duct and main pancreatic duct in second portion of duodenum near pancreatic head. Ampullary cancers may block the bile duct resulting in clinical jaundice and sometimes diagnosis at an earlier stage. Overall,  ampullary cancers have a better prognosis than pancreatic adenocarcinoma.