Pancreatic Diseases

Published on 16/04/2015 by admin

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Last modified 22/04/2025

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14 Pancreatic Diseases

Anatomy of the Pancreas

image

Pancreas in Situ

Parts and Landmarks

• Head (includes uncinate process), neck, body, tail
• Uncinate process lies behind superior mesenteric artery and anterior to aorta.
• Neck overlies superior mesenteric artery and vein and portal vein.
• Development

image Two endodermal gland buds of caudal foregut merge to form pancreas.
image Buds rotate with foregut.
image Dorsal bud forms body and tail.
image Ventral bud makes head; uncinate process rotates behind superior mesenteric artery.
image Original mesentery fuses with posterior peritoneum, and pancreas becomes retroperitoneal.

Location and Locale of the Pancreas

• Retroperitoneal and posterior to stomach: typically nonpalpable on physical examination
• Neck of pancreas overlies L1 and L2 vertebral bodies in the transpyloric plane.
• Head is to the right of and inferior to transpyloric plane.
• Body and tail are to the left and above transpyloric plane.

Duct System

Main Pancreatic Duct

• Begins in tail, runs medially into head
• Turns inferiorly, closely related to bile duct
• Ducts unite to form hepatopancreatic ampulla (of Vater).
• Ampulla empties into descending duodenum at the major duodenal papilla.
• Smooth muscle sphincter of pancreatic duct around terminal portion
• Smooth muscle sphincter lies around terminal bile duct.
• Hepatopancreatic sphincter (of Oddi) around hepatopancreatic ampulla

Accessory Pancreatic Duct (Variable)

• Can open into duodenum at minor duodenal papilla
• Accessory duct more often joins main duct (~60%).
• If main duct is small, and there is no juncture, accessory duct can carry majority of secretion.

Functional Anatomy

• Tubuloacinar gland structure with a variety of cell types, including intermingled islets of Langerhans
• Parasympathetic and sympathetic nerves are distributed to islets and acini.
• Cells’ secretions are controlled by endocrine and autonomic nervous activities.

Exocrine Functions

• Mediated by secretin and cholecystokinin formed by duodenal and jejunal epithelium
• Acinar cells secrete amylase, lipase, trypsinogen, chymotrypsinogen, carboxypeptidase, and Cl−.
• Ductal cells secrete HCO3−.
• Some secretomotor input comes from vagal parasympathetic fibers.

Endocrine Functions

• Alpha cells secrete glucagon.
• Beta cells (central islets) secrete insulin.
• Delta cells secrete somatostatin.
• F or PP cells secrete pancreatic polypeptide.
• Islet cells also produce vasoactive intestinal peptide (VIP), serotonin, neuropeptide Y, and gastrin releasing peptide (GRP).

Innervation

image Both parasympathetic and sympathetic efferent fibers are distributed to islets.
image Parasympathetic: vagus

image Preganglionic fibers from left and right vagal trunks distributed through celiac plexus
image Postganglionic: ganglion cells associated with ductal smooth muscle, islets, acini

• Sympathetic fibers

image Preganglionic from T7-T10 segments, distributed via splanchnic nerves to celiac ganglion
image Postganglionic fibers distributed though celiac plexus along arterial branches
image Terminations on vascular smooth muscle, islets, acini

Vessels and Lymphatics

image

Arteries of Liver, Pancreas, and Spleen

Arterial Supply

• Head supplied by anterior and posterior branches of superior and inferior pancreaticoduodenal arteries, branches (respectively) of the gastroduodenal (celiac axis) and superior mesenteric arteries
• Body supplied by great, inferior, and caudal pancreatic arteries and branches of splenic artery
• Tail supplied by splenic, gastroepiploic, and dorsal pancreatic arteries
• Greatest blood flow to islet cells, then acini
image

Veins of Stomach, Pancreas, and Spleen

Venous Drainage

• Into portal system by numerous branches, great pancreatic vein and others, draining first into splenic vein (left portal)
• Superior and inferior pancreaticoduodenal veins from head and neck region drain into superior mesenteric vein (right portal).
image

Lymph Vessels and Nodes of Pancreas

Lymphatic Drainage

• Nodes on surface and borders drain into celiac and superior mesenteric nodes.
• Upstream drainage into cisterna chyli and thoracic duct

Clinical Correlates

Pancreatitis

Acute

• Stones and alcohol consumption most common causes in U.S.
• Other causes include

image Endoscopic retrograde cholangiopancreatography (ERCP [Chapter 8, Biliary Diseases]), trauma
image Hyperlipidemia, hypercalcemia, medications
image Viruses and Ascaris lumbricoides and Cephalotaxus sinensis parasitism

• Symptoms: abdominal pain radiating to back, nausea, vomiting, anorexia
• 10% mortality, 50% for hemorrhagic
• No apparent cause? Cancer a concern

Chronic

• Associated with irreversible parenchymal fibrosis
• Chronic alcohol consumption most common cause of chronic pancreatitis, idiopathic 2nd
• Exocrine tissue calcified/fibrotic, islets spared
• Advanced disease: lakes, dilations, and stenoses in duct(s)
• Pain most common, with anorexia, weight loss, malabsorption, steatorrhea, recurrent acute pancreatitis
• Diagnosis

image CT shows calcifications and atrophy.
image Ultrasound shows dilated ducts, cysts, and atrophy.
image ECRP is very sensitive for chronic disease.

Pancreatic Cancer

image

Carcinoma of Pancreas

Adenocarcinoma

• Predominantly male disease
• Typically found in 6th or 7th decade
• Most common symptoms: weight loss, jaundice, pain
• Most common risk factor: tobacco use
• ~20% survival rate at 5 years with resection
• Lymphatic spread usually occurs first.
• About 70% in head of pancreas
• 90% ductal adenocarcinoma

Endocrine Neoplasms

• Functional endocrine pancreatic tumors represent 2/3 of endocrine neoplasms; 1/3 are nonfunctional.
• Most common in pancreatic head
• Tumors respond to debulking.
• Liver most common site of metastasis for all types
• 5 fluorouracil (5-FU) and streptozocin chemotherapy work well for all.
• Insulinoma

image Most common islet cell tumor, >85% benign
image Symptoms (Whipple’s triad): fasting hypoglycemia, hypoglycemic symptoms (catechol surge, elevated heart rate, sweating), relieved by glucose

• Gastrinoma (Zollinger-Ellison syndrome: see next page)
• Somatostatinoma

image Very rare, most are malignant
image Symptoms: diabetes, gallstones, steatorrhea, hypochlorhydria
image Most common in head

• Glucagonoma

image Most are malignant.
image Symptoms: diabetes, weight loss, stomatitis, dermatitis

• VIPoma (Werner-Morrison syndrome)

image Most are malignant.
image Symptoms: diarrhea, hypokalemia, achlorhydria

image

Zollinger-Ellison Syndrome

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14 Pancreatic Diseases

Anatomy of the Pancreas

image

Pancreas in Situ

Parts and Landmarks

• Head (includes uncinate process), neck, body, tail
• Uncinate process lies behind superior mesenteric artery and anterior to aorta.
• Neck overlies superior mesenteric artery and vein and portal vein.
• Development

image Two endodermal gland buds of caudal foregut merge to form pancreas.
image Buds rotate with foregut.
image Dorsal bud forms body and tail.
image Ventral bud makes head; uncinate process rotates behind superior mesenteric artery.
image Original mesentery fuses with posterior peritoneum, and pancreas becomes retroperitoneal.

Location and Locale of the Pancreas

• Retroperitoneal and posterior to stomach: typically nonpalpable on physical examination
• Neck of pancreas overlies L1 and L2 vertebral bodies in the transpyloric plane.
• Head is to the right of and inferior to transpyloric plane.
• Body and tail are to the left and above transpyloric plane.

Duct System

Main Pancreatic Duct

• Begins in tail, runs medially into head
• Turns inferiorly, closely related to bile duct
• Ducts unite to form hepatopancreatic ampulla (of Vater).
• Ampulla empties into descending duodenum at the major duodenal papilla.
• Smooth muscle sphincter of pancreatic duct around terminal portion
• Smooth muscle sphincter lies around terminal bile duct.
• Hepatopancreatic sphincter (of Oddi) around hepatopancreatic ampulla

Accessory Pancreatic Duct (Variable)

• Can open into duodenum at minor duodenal papilla
• Accessory duct more often joins main duct (~60%).
• If main duct is small, and there is no juncture, accessory duct can carry majority of secretion.

Functional Anatomy

• Tubuloacinar gland structure with a variety of cell types, including intermingled islets of Langerhans
• Parasympathetic and sympathetic nerves are distributed to islets and acini.
• Cells’ secretions are controlled by endocrine and autonomic nervous activities.

Exocrine Functions

• Mediated by secretin and cholecystokinin formed by duodenal and jejunal epithelium
• Acinar cells secrete amylase, lipase, trypsinogen, chymotrypsinogen, carboxypeptidase, and Cl−.
• Ductal cells secrete HCO3−.
• Some secretomotor input comes from vagal parasympathetic fibers.

Endocrine Functions

• Alpha cells secrete glucagon.
• Beta cells

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