Biliary Tract and Pancreas

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    General PathologyBiliary Tract and Pancreas1 December 07

    Biliary Tract

    Bile

    Two major functions

    o Elimination of bilirubin, excess cholesterol, and

    xenobiotics that are insufficiently water soluble to be

    excreted in urine

    o Emulsification of dietary fat in the gut by bile acids

    (cholic acid, chenodeoxycholic acid)

    Unconjugated Conjugated

    Reabsorbed in terminal ileum (enterohepatic circulation)

    Cholestasis

    Systemic retention of not only bilirubin but also other solutes

    eliminated in bile, particularly bile salts and cholesterol

    Due to hepatocellular dysfunction or biliary obstruction Accumulation of bile pigment within the hepatic parenchyma

    Kupffer cells

    Bile ductular proliferation

    Bile lakes

    Portal tract fibrosis

    Secondary Biliary Cirrhosis

    Most common cause is extrahepatic cholelithiasis

    Biliary atresia, malignancies of the biliary tree and head of

    the pancreas, and strictures

    Cholestasis

    Bile duct proliferation with surrounding neutrophils

    Periportal fibrosis

    Primary Biliary Cirrhosis

    Middle-aged women

    M:F = 1:10

    Possibly autoimmune

    o Autoantibodies to mitochondrial pyruvate

    dehydrogenase 90% Insidious onset, usually presenting with pruritus

    Hyperbilirubinemia, jaundice, cirrhosis late

    alkaline phosphatase, cholesterol

    Figure 1-Nonsuppurative, granulomatous destruction of medium-sized

    intrahepatic bile ducts = florid duct lesion

    Primary Sclerosing Cholangitis

    Inflammation, obliterative onion-skin fibrosis, and segmental

    dilatation of the obstructed intrahepatic and extrahepatic bile

    ducts

    String of beads on ERCP

    70% associated with inflammatory bowel disease,

    particularly ulcerative colitis

    M:F = 2:1, third through fifth decades

    Progressive fatigue, pruritus, jaundice

    Chronic course

    Increased risk for cholangiocarcinoma

    Cholelithiasis

    Very common

    Cholesterol stones

    o Bile is supersaturated with cholesterol

    o Gallbladder stasis

    o F>Mo Obesity

    o Advancing age

    Pigment stones calcium bilirubinate salts

    o Asian more than Western

    o Chronic hemolytic syndromes

    Clinical Featureso Asymptomatic

    o Biliary colic

    o Cholecystitis

    o Gallstone ileus

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    Cholecystitis

    Acute calculous

    o Obstruction of GB neck or cystic duct

    o RUQ pain radiating to right shoulder

    o Fever, nausea, leukocytosis

    o Potential surgical emergency

    Acute acalculous seriously ill pts

    Chronic

    o Recurrent attacks of pain

    o Nausea and vomiting

    o Associated with fatty meals

    Choledocholithiasis

    Stones within the biliary tree

    West from gallbladder

    Asia primary ductal and intrahepatic stone formation

    Symptoms due to:

    o Biliary obstruction

    o Pancreatitis

    o Cholangitis

    o Hepatic abscess

    Cholangitis

    Acute inflammation of bile ducts

    Due to biliary obstruction, usually choledocholithiasis

    Bacterial infection from gut, i.e., gram negative aerobes

    o Fever, chills, abdominal pain, jaundice

    Latin America and Near East: Fasciola hepatica,

    schistosomiasis

    Far East: Clonorchis sinensis, Opisthorchis viverrini

    AIDS: cryptosporidiosis

    Biliary Atresia

    1/3 of cases of neonatal cholestasis

    1 in 10,000 live births

    Complete obstruction of bile flow caused by destruction o

    absence of all or part of the extrahepatic bile ducts

    Acquired inflammatory disorder

    Normal stools to acholic stools

    Bile ductular proliferation on liver bx

    Cirrhosis by 3 to 6 months of age.

    Require liver transplantation

    Gallbladder Carcinoma

    Seventh decade

    F>M

    Discovered at late stage, usually incidental

    Exophytic and infiltrating types

    Adenocarcinoma

    Local extension into liver, cystic duct, portahepatic LNs

    Mean 5 yr survival 1%

    Cholangiocarcinoma

    Older pts

    M>F

    Painless jaundice, N/V, weight loss

    Opisthorchis sinensis (liver fluke),inflammatory bowe

    disease

    Tumors usually small at dx yet not resectable Klatskin tumor arises at bifurcation

    Adenocarcinoma

    Mean survival 6 to 18 months

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    Pancreas

    Brief History

    Herophilus, Greek surgeon first described pancreas.

    Wirsung discovered the pancreatic duct in 1642.

    Pancreas as a secretory gland was investigated by Graaf in

    1671.

    R. Fitz established pancreatitis as a disease in 1889.

    Whipple performed the first pancreatico-duodenectomy in

    1935 and refined it in 1940.

    Pancreas

    Gland with both exocrine and endocrine functions

    6-10 inch in length

    60-100 gram in weight

    Location: retro-peritoneum*, 2nd lumbar vertebral level Extends in an oblique, transverse position

    Parts of pancreas: head, neck, body and tail

    Embryology Endodermal origin

    Develops from ventral and dorsal pancreatic buds

    Ventral bud becomes the uncinate process and inferior head

    of pancreas

    Dorsal bud becomes superior head, neck, body and tail

    Ventral bud duct fuses with dorsal bud duct to become mail

    pancreatic duct (Wirsung)

    Head of Pancreas

    Includes uncinate process

    Flattened structure, 2 3 cm thick

    Attached to the 2nd and 3rd portions of duodenum on the

    right

    Emerges into neck on the left

    Border b/w head & neck is determined by GDA insertion

    SPDA and IPDA anastamose b/w the duodenum and the rt

    lateral border

    Neck of Pancreas

    2.5 cm in length

    Straddles SMV and PV

    Antero-superior surface supports the pylorus

    Superior mesenteric vessels emerge from the inferior border

    Posteriorly, SMV and splenic vein confluence to form porta

    vein

    Posteriorly, mostly no branches to pancreas

    Body of Pancreas

    Elongated, long structure

    Anterior surface, separated from stomach by lesser sac

    Posterior surface, related to aorta, lt. adrenal gland, lt. rena

    vessels and upper 1/3rd of lt. kidney

    Splenic vein runs embedded in the post. Surface

    Inferior surface is covered by tran. mesocolon

    Tail of Pancreas

    Narrow, short segment

    Lies at the level of the 12 th thoracic vertebra

    Ends within the splenic hilum

    Lies in the splenophrenic ligament

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    Anteriorly, related to splenic flexure of colon

    May be injured during splenectomy (fistula)

    Pancreatic Duct

    Main duct (Wirsung) runs the entire length of pancreas

    Joins CBD at the ampulla of Vater

    2 4 mm in diameter, 20 secondary branches

    Ductal pressure is 15 30 mm Hg (vs. 7 17 in CBD) thuspreventing damage to panc. duct

    Lesser duct (Santorini) drains superior portion of head and

    empties separately into 2nd portion of duodenum

    Arterial Supply of the Pancreas

    Variety of major arterial sources (celiac, SMA and splenic)

    Celiac Common Hepatic Artery Gastroduodenal Artery

    Superior pancreaticoduodenal artery which divides into

    anterior and posterior branches

    SMA Inferior pancreaticoduodenal artery which divides

    into anterior and posterior branches

    Anterior collateral arcade b/w anterosuperior and

    anteroinferior PDA

    Posterior collateral arcade b/w posterosuperior and

    posteroinferior PDA

    Body and tail supplied by splenic artery by about 10

    branches

    Three biggest branches are

    o Dorsal pancreatic artery

    o Pancreatica Magna (midportion of body)

    o Caudal pancreatic artery (tail)

    Venous Drainage of Pancreas

    Follows arterial supply

    Anterior and posterior arcades drain head and the body

    Splenic vein drains the body and tail

    Major drainage areas are

    o Suprapancreatic PV

    o Retropancreatic PV

    o Splenic vein

    o Infrapancreatic SMV

    Ultimately, into portal vein

    Lymphatic Drainage

    Rich periacinar network that drain into 5 nodal groups

    o Superior nodes

    o Anterior nodes

    o Inferior nodes

    o Posterior PD nodes

    o Splenic nodes

    Innervation of Pancreas

    Peptidergic neurons that secrete amines and peptides(somatostatin, vasoactive intestinal peptide, calcitonin gene

    related peptide, and galanin

    Rich afferent sensory fiber network

    Ganglionectomy or celiac ganglion blockade interrupt these

    somatic fibers (pancreatic pain*)

    Peptidergic neurons that secrete amines and peptides

    (somatostatin, vasoactive intestinal peptide, calcitonin gene

    related peptide, and galanin

    Rich afferent sensory fiber network

    Ganglionectomy or celiac ganglion blockade interrupt these

    somatic fibers (pancreatic pain*)

    Histology-Exocrine Pancreas

    2 major components acinar cells and ducts

    Constitute 80% to 90% of the pancreatic mass

    Acinar cells secrete the digestive enzymes

    20 to 40 acinar cells coalesce into a unit called the acinus

    Centroacinar cell (2nd cell type in the acinus) is responsibl