Embryology of pancreas
Develops from endoderm of duodenum. Two pouches develop (ventral and dorsal) that then rotate and fuse by 8th week.
Ventral pancreas malrotates and encircles 2nd portion of duodenum -> pancreatitis, bowel obstruction, peptic ulcer. Tx: duodenoduodenostomy (bypass)
Failure to fuse two duct systems, such that duct of Santorini (normally accessory duct) becomes the main duct. Majority are asymptomatic, but if it results in inadequate drainage -> chronic pain, recurrent pancreatitis
Exocrine function of pancreas
Acinar cells secrete enzymes. Centroacinar and ductal cells secrete water and electrolytes. Overall 1-5 L/day of isosmotic, pH 8 fluid.
Cephalic phase of digestion
Stimuli of sight/smell of food -> vagal activation -> gastric acid production -> duodenal acidification -> secretin release -> pancreatic HCO3 release
Gastric phase of digestion
Antral distention and protein -> gastrin -> gastric acid production -> duodenal acidification -> secretin release -> pancreatic HCO3 release
Duodenal acid and bile stimulate secretin, duodenal fat/protein release CCK -> release of pancreatic enzymes
Endocrine function of pancreas
Insulin (beta cells), glucagon (alpha cells), somatostatin (delta cells), pancreatic polypeptide
Clinical uses of somatostatin
1. Tx sx of neuroendocrine tumors (e.g. carcinoid, VIPoma, gastrinoma) 2. Convert high-output fistulae to low-output fistulae
Drugs that can cause pancreatitis
Isoniazid, estrogens, azathioprine (Imuran), HCTZ, sulfonamides, pentamidine (antifungal for PCP), didanosine (HAART), chemo for ALL, Depakote
What is a sentinel loop on XRay?
Distention and/or air-fluid levels near a site of abdominal distention. Can be seen in pancreatitis due to secondary ileus
Causes of chronic pancreatitis other than alcohol
HyperPTH, CF, congenital pancreatic anomalies, hemochromatosis. NOT commonly gallstones though
Pancreatic pseudocyst definition
Fluid collection without epithelial lining
Pancreatic pseudocyst treatment
1/3 resolve on own with TPN and NPO. After 4 weeks (wall has matured) can do internal drainage: RenY cyst-jejunostomy or cyst-gastrostomy
Pancreatic adenocarcinoma epi
Arises from exocrine pancreas. M > F, older, blacks > whites, smoking risk factor, most occur in the head, association with MEN1.
Migratory thrombophlebitis assoc with GI adenocarcinoma, esp pancreatic
Tumor markers for pancreatic adenocarcinoma
Ca 19-9, alk phos
Removal of gallbladder, CBD, antrum of stomach, duodenum, proximal jejunum and head of pancreas
Palliative procedures for pancreatic cancer
Relieve biliary and/or duodenal obstruction. Pain control with chemical splanchicectomy (sympathetic nerves to pancreas)
Females age 40-60 yrs, more commonly in the body/tail. Malignant potential, but better prognosis than adencarcinoma. Tx: resection.
Older/middle aged women, presents with vague abdominal sx. Two types: serous = benign, mucinous = malignant potential. Tx: resection
Majority are benign, solitary lesions. Diagnosis: fasting serum insulin > 25. To distinguish from exogenous insulin, check C-peptide. Tx: surgical resection
Causes ZES. Majority malignant/multiple. About 20% assoc with MEN1. Dx: serum gastrin > 1000. Tx: resection difficult bc often multiple; PPI.
Causes achlorhydria and watery, secretory diarrhea -> hypokalemia. Most are malignant. Tx: surgery, chemo; octreotide (somatostatin analogue).
Why does VIPoma cause watery diarrhea?
VIP is a potent stimulator of gut cyclic adenosine monophosphate (cAMP) production, which leads to massive secretion of water and electrolytes (mainly potassium).
Why does VIPoma cause achlorhydria?
In the stomach, VIP inhibits histamine- and pentagastrin-stimulated acid secretion.
Rare; most are malignant, large primary tumors that metastasize. Causes 4Ds – DM (hyperglycemia), dermatitis (necrolytic migratory erythema), deep vein thrombosis (DVT) and depression. Dx: glucagon > 1000
Very rare, large tumor that metastasizes. Gallstones, diarrhea, hypochlorhydria, weight loss, abdominal cramps. Dx: somatostatin > 1000