Chapter 19 The Pancreas

Pancreas Transversely oriented retroperitoneal organ extending from the C loop of the duedenum to the hilum of the spleen Head, neck, body, tail Pancreatic duct system is highly variable 80-85% exocrine Self-digestion is prevented by several mechanisms

Congenital anomalies Agenesis Pancreas Divisum Annular pancreas Ectopic pancreas

Pancreatitis Inflammation in the pancreas associated with injury to the exocrine pancreas Acute reversible injury associated with inflammation bilary tract disease and alcoholism- 80% less common – obstruction of the duct system, medications, infections, metabolic disorders, ischemic injury, trauma, inherited alterations in genes encoding pancreatic enzymes and their inhibitors mutations in the cationic trypsinogen gene or the gene for the trypsin inhibitor

Acute pancreatitis Microvascular leakage causing edema Necrosis of fat by lipolytic enzymes Acute inflammation Proteolytic destruction of parenchyma Destruction of blood vessels and hemorrhage Acute necrotizing or hemorrhagic Autodigestion of the pancreatic substance by inappropriately activated pancreatic enzymes Trypsinogen Three possible causes of activation duct obstruction acinar cell injury defective intracellular transport Clinical features abdominal pain-constant anorexia, NV, systemic symptoms related to release of toxic enzymes, cytokines, medicators – explosive activaiton of the inflammatory response amylase, lipase resting the pancreas

Chronic Pancreatitis Inflammation with irreversible destruction of exocrine parenchyma, fibrosis, and later destruction of the endocrine parenchyma Long-term alcohol abuse is most common cause Other causes obstruction tropical hereditary CF Pathogenesis ductal obstructions by concretions toxic effects oxidative stress Parenchymal fibrosis, reduced number and size of acini with relative sparing of the islets of Lngerhans and variable dilation of the pancreatic ducts Lymphoplasmactic sclerosing pancreatitis ( auto-immune) Clinical features variable recurrent attacks of pain, persistent abdominal and back pain triggers- alcohol abuse, overeating, drugs

Non-neoplastic Cysts Congenital polycytic disease von Hippel-Lindau disease Pseudocysts localized collections of necrotic-hemorrhagic material rich in pancreatic enzymes No epithelial lining

Cystic neoplasms Serous cystadenomas Mucinous cystic neoplasms Intraductal papillary muinous neoplasms Solid-pseudopapillary neoplasm

Pancreatic Carcinoma Infiltrating ductal adenocarcinoma Fourth leading cause of caner deaths in the US Precursor – pancreatic intraepithelial neoplasms Cigarette smoking Chronic pancreatitis Diabetes mellitus Elderly Familial clustering Carcinomas of the body and tail of the pancreas do not impinge on the biliary tract and hence remain silent for some time Moderately to poorly differentiated adenocarcinoma forming abortive tubular structures or cell clusters and slowing an aggressive, deeply infiltrative growth pattern Often remain silent until they invade into adjacent structures Trousseau sign – migratory thrombophlebitis Acinar cell carcinoma pancreatoblastoma