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Kingdom of Bahrain Arabian Gulf University College of Medicine and Medical Sciences. General Surgery The Pancreas. Ali Jassim Alhashli. Anatomy and Embryology. Embryology: Pancreas develop from (duodenal endoderm) at 4 th week of gestation.
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Kingdom of BahrainArabian Gulf UniversityCollege of Medicine and Medical Sciences General Surgery The Pancreas Ali Jassim Alhashli
Anatomy and Embryology • Embryology: • Pancreas develop from (duodenal endoderm) at 4th week of gestation. • 2 buds will form, they will rotate and fuse by 8th week: • Ventral pancreatic bud: forms part of the head + uncinate process. • Dorsal pancreatic bud: forms remaining of the head + neck + body + tail. • Anomalies: • Pancreas divisum: failure of ventral and dorsal pancreatic buds to fuse. Therefore, majority of pancreatic drainage occurs via accessory papilla and accessory duct (of Santorini). • Annular pancreas: it results in duodenal obstruction (ring formed around 2nd part of duodenum) which results in post-prandial vomiting.
Anatomy: • It is a retroperitoneal organ which is located posterior to the stomach, transverse colon and lesser omentum at the level of L2. • Parts of the pancreas: • Head: includes uncinate process; contained within the curve of 2nd part of duodenum. • Neck: anterior to superior mesenteric vessels. • Body. • Tail: it enters splenorenal ligament this it is adjacent to splenichilum and susceptible to injury during splenectomy. • Blood supply: • Head: • Anterior and posterior superior pancreaticoduodenal arteries → from gastroduodenal artery. • Anterior and posterior inferior pancreaticoduodenal arteries → from superior mesenteric artery. • Neck, body and tail: splenic artery. • Innervation: • Sympathetic: celiac plexus (via splanchnic nerves). • Parasympathetic: vagus nerve. Anatomy and Embryology
Histology • Exocrine pancreas: • It secretes 1-2 L/day of clear, isosmotic, alkaline (pH 7.0 – 8.3) fluid containing digestive enzymes (amylase, lipase, trypsin, chymotrypsin and carboxypeptidase). • Endocrine (Islets of Langerhans = 2% of pancreatic weight): • Alpha cells: glucagon (glycogenolysis and release of glucose). • Beta cells: insulin (glucose absorption and storage). • Delta cells: somatostatin (inhibitory functions of GI tract).
Acute Pancreatitis • Definition: it is the acute inflammation of the pancreas caused by its autodigestion by proteolytic enzymes. • Causes: PANCREATITIS • P: Posterior perforation of peptic ulcer. • A: Alcohol (50%). • N: Neoplasm. • C: Cholelithiasis (30%). • R: Renal disease (end stage). • E: ERCP. • A: Anorexia (malnutrition). • T: Trauma. • I: Infections. • T: Toxins (drugs = MEDVIPS → Methyldopa/Metronidazole, Estrogen, Didanosine, Valproic acid, Isoniazid, Pentamidine and Sulfonamides). • I: Idiopathic (10%). • S: Surgery/Scorpion bite.
Acute Pancreatitis • Signs and symptoms: • Severe, constant epigastric pain radiating to the back and relieved when leaning forward. • Nausea and vomiting. • Cullen’s sign: periumbilical bluish discoloration; Turner’s sign: bluish discoloration of the flank; fox’s sign: bluish discoloration of the inguinal ligament. Notice that these signs indicate severe hemorrhagic pancreatitis. • Diagnosis: • Laboratory investigations: CBC (for leukocytosis), amylase/lipase (lipase is more specific; amylase considered diagnostic if X3 times higher than upper border), LFTs and bilirubin, Urea/creatinine/electrolytes and serum lipids. • Imaging: • AXR: Sentinel loop sign and colon cutoff sign. • Ultrasound. • CT-scan (best): it shows the degree of pancreatitis and if any complications are present (pseudocyst; necrosis: IV contrast is not taken up by dead pancreatic tissue; abscess). • Pancreatic abscess: • Collection of pus in the pancreas. • Patient has unresolving pancreatitis, fever and epigastric mass might be felt. • Do abdominal CT-scan with aspiration and send the sample for Gram stain and culture. • Common organisms are Gram (-) such as E.coli, Pseudomonas and Klebsiella. Gram (+) organisms might also cause abscess such as S.aureus. • Treatment: placement of percutaneous drainage + antibiotics.
Acute Pancreatitis • Differential diagnosis: • Acute cholecystitis. • Peptic ulcer disease (± perforation). • Myocardial infarction (inferior wall). • Treatment: • Bed rest and NPO. • Analgesia (don’t use morphine). • Fluid resuscitation and monitoring of electrolytes. • Antibiotics are given when patient has necrotizing pancreatitis (CT-guided aspiration). • Surgery indicated when there are complications of pancreatitis: hemorrhage, pseudocyst or infected necrosis. • Prognosis: Ranson’s criteria
Chronic Pancreatitis • Definition: it is the chronic inflammation of the pancreas which results in pancreatic shrinkage, fibrosis and calcification thus exocrine and endocrine functions are lost. • Causes: commonly associated with alcohol abuse (in 70% of cases). This chronic inflammation might result from recurrent attacks of acute pancreatitis. Notice that gallstones are not a common cause for chronic pancreatitis. • Signs and symptoms: • Recurrent or constant epigastric pain which may or may not radiate to the back. • Malabsorption and malnutrition. Therefore, patient has steatorrhea (25% of cases) and deficiency of fat-soluble vitamins (A, D, K and E). • New onset of type-I diabetes mellitus (1/3 of cases). • Diagnosis: • AXR: pancreatic calcifications. • CT-scan: atrophy and calcifications. • ERCP: chain-of-lakes pattern (ductal irregularities with dilation and stenosis). • Fecal fat analysis: for elastase levels. • Indications for surgery: • Pseudocyst: it is a nonepithelialized, encapsulated pancreatic fluid collection. Chance of spontaneous recovery is less when pseudocyst is larger than 5 cm → internal drainage is required via percutaneous drain, operative drainage or cyst gastrostomy (if it is adherent to the stomach). Surgery is indicated when there is: rupture, infection, hemorrhage or it is enlarging. • Persistent pain. • GI or biliary obstruction. • Treatment: • Medical: analgesia + insulin + replacement of pancreatic enzymes. • Surgical: • Pain relief: celiac plexus block. • Ampullary procedures: ERCP with endoscopic sphincterotomy. • Resection of portions of pancreas: • Whipple procedure: pancreaticoduodenoctomy with hepatojejunostomy, pancreaticojejunostomy and gastrojejunostomy.
Pancreatic Adenocarcinoma • Pancreatic cancer arises from exocrine pancreas. 2/3 of tumors occur in the head of pancreas thus patients will present early as this causes biliary obstruction. • Risk factors: • Increased age (< 60 years). • Male gender. • African-Americans. • Smoking (doubles the risk). • Diabetes. • Chronic pancreatitis. • Alcohol abuse. • Signs and symptoms: • Epigastric pain radiating to the back. • Weight loss and anorexia. • New onset of diabetes. • Malnutrition with steatorrhea. • Painless jaundice (due to ampullary obstruction). This results in what is known as Courvoisier’s sign (palpable, nontender, distended gallbladder). • Migratory thrombophlebitis (Trousseau’s syndrome): vessel inflammation –due to blood clot- which is recurrent or appearing in different locations over time.
Pancreatic Adenocarcinoma • Diagnosis: • Labs: increased LFTs, alkaline phosphatase and direct bilirubin. • Study of choice: abdominal CT-scan with IV contrast. • You can follow up the patient with the tumor marker CA 19-9. • Treatment: • Tumors of the head of pancreas: Whipple procedure (although most tumors cannot be resected at time of diagnosis!). • Tumors of body/tail of pancreas: near-total pancreatectomy. • Post-operatively: chemotherapy (5-FU) + external-beam radiation. • If tumor cannot be surgically removed → palliative treatment to relieve symptoms: • Relieve biliary obstruction: ERCP with biliarystenting. • Relieve duodenal obstruction: gastrojejunostomy – bypass procedure. • To control the pain: splanchnic nerve block. • Prognosis: • Resectable tumor: 12 months with 5-year survival rate = 15%. • Unresectable tumor: 6 months with 5-year survival rate = > 3%
Islet Cell Tumors • Insulinoma: • Definition: It is a benign neoplasm of beta-cell of Islet of Langerhans which results in increased production of insulin. It is the most common islet cell tumor. • Most of these tumors are solitary but if they are associated with MEN-1 (Parathyroid, Pancreas, Pituitary) → they can be multiple. • Symptoms related to hypoglycemia triggered catecholamine release. Insulinoma is characterized by Whipple’s triad: • Symptoms of hypoglycemia with fasting. • Relief of symptoms with eating. • Fasting glucose > 50 mg/dL • Diagnosis: • Fasting serum insulin < 10 µU/ml. • Fasting insulin-to-glucose ratio < 0.3 • C-peptide levels should be measured to rule out exogenous administration of insulin. • Abdominal CT-scan or MRI. • Treatment: surgical resection of the tumor. Diazoxide (potassium channel activator) can be used to relief symptoms of hypoglycemia as it blocks the release of insulin from pancreas.
Islet Cell Tumors • Gastrinoma (also known as Zolinger-Ellison syndrome): • Definition: it is a tumor which results in increased production of gastrin. It is the 2nd most common islet cell tumor. • This tumor is usually multiple and 60% are malignant. It is located in gastrinoma triangle which is bordered by: • Junction of 2nd and 3rd parts of the duodenum. • Superior mesenteric artery. • Cystic duct. • Signs and symptoms (mostly those of PUD): • Epigastric pain which becomes worst after eating food. • Profuse watery diarrhea. • Diagnosis: • Fasting serum gastrin< 500 pg/ml • Secretin stimulation test causes paradoxical increase in gastrin level. • Ulcers in unusual locations (3rd part of duodenum or jejunum). • Octreotide scan: most gastrinomas over-express somatostatin receptor type-II which can be targeted by In-III labeled octreotide. • Treatment: • PPI (to relieve symptoms of PUD). • Surgical resection. • Chemotherapy.
Islet Cell Tumors • Vipoma: • Definition: malignant neoplasm in which there is increased production of (VIP: Vasoactive Intestinal Peptide). At time of diagnosis, most patients have metastasis to lymph nodes and liver. • It is also known as WDHA syndrome: • WD: Watery Diarrhea. • H: Hypokalemia (which results in arrhythmias, muscle fasiculations and tetany). • A: Achlorhydria. • Diagnosis: • Fasting serum VIP < 800 pg/ml. • Treatment: • Control diarrhea with octreotide. • Surgical removal of the tumor with chemotherapy. • Glocagonoma: • Definition: it is a rare malignant tumor of alpha cell of islet of Langerhans resulting in increased production of glucagon. Most patients have metastasis to lymph nodes and liver at time of diagnosis. • Signs and symptoms: • Hyperglycemia. • Weight loss (duo to low amino acid levels). • Necrolytic migratory erythema: necrosis of superficial epidermis and swollen epidermal cells. • Mucositis: painful inflammation and ulceration of mucous membranes lining the digestive tract. • Anemia. • Diagnosis: • Fasting serum glucagon < 1000 pg/ml. • Skin biopsy to confirm presence of necrolytic migratory erythema. • Treatment: • Octreotide: to inhibit release of glucagon. • Surgical resection and chemotherapy.