Liver and Biliary Tract Pathology

Congenital Disorders: Extrahepatic Biliary Atresia Most common cause of pathologic infant jaundice; common reason for pediatric liver transplantation Definition: total or partial loss of permeable bile ducts between porta hepatis and duodenum Typically presents with symptoms at 1-2 months of age Stenotic or atretic portions of extrahepatic biliary tree cause chronic extrahepatic large duct obstruction Infectious or autoimmune etiology Positive stains: CD56 Molecular: 10% have mutations in Jagged 1 gene (associated with Alagille’s syndrome)

Marked cholestasis with intrahepatic bile duct proliferation, fibrosis, and cirrhosis. This liver was rock hard. The dark green color comes from formalin acting on bile pigments in the liver from marked cholestasis, turning bilrubin to biliverdin.

Microscopically, extrahepatic biliary atresia leads to this appearance in the liver, with numerous brown-green bile plugs, bile duct proliferation (seen at lower center), and extensive fibrosis.

Congenital Disorders: Polycystic liver disease Autosomal dominant, associated with autosomal dominant polycystic kidney disease (71-93%) and defect in ADPKD1 gene on #16 Cysts don’t communication with biliary tree 80% occur in females 1-7% risk of adenocarcinoma if coexisting Caroli’s disease; otherwise extremely rare Complications: infection, cholangiocarcinoma, squamous cell carcinoma Gross: multiple variably sized unilocular cysts, liver rarely is massively enlarged

Numerous cysts appear in this liver from a patient with dominant polycystic kidney disease (DPKD). Less commonly the pancreas is involved. These patients with DPKD can also have berry aneurysms in the cerebral arteries.

von Meyenburg complex Also called bile duct hamartoma or microhamartoma Incidental finding in 6% of adults and 1% of children at autopsy. Associated with autosomal dominant polycystic hepatorenal disease, congenital hepatic fibrosis and Caroli’s disease Rarely associated with neoplastic transformation to hyperplasia, adenoma and cholangiocarcinoma Positive stains: mucin (variable)  

Gross: single or multiple (20% have 4+ nodules) well circumscribed nodules, subcapsular, gray-white, occasionally green; often less than 5 mm Micro: periportal small clusters of modestly dilated bile ducts, often angulated, in fibrous stroma; may contain intraluminal bile; epithelial cells are bland; usually no/minimal inflammatory infiltrate, no atypia

Metabolic diseases: Alpha-1-antitrypsin deficiency Autosomal recessive disease, causing low serum levels of alpha-1-antitrypsin (AAT), and leading to emphysema (80%) and liver disease AAT is a small, 394 amino acid, plasma glycoprotein, synthesized predominantly by hepatocytes, encoded by a gene on #14 AAT is a protease inhibitor (Pi), which inhibits neutrophilic elastase released at sites of inflammation; also inhibits trypsin Although there are 75 AAT forms, PiMM (normal phenotype) is present in 90% of population PiZZ: 1 per 7,000; have 10-15% of normal AAT levels, are at high risk for clinical disease, but only 10% get clinical disease PiZZ: hepatic syndromes range from neonatal hepatitis (10%), biliary atresia (intra- or extrahepatic), fibrosis, childhood cirrhosis; 2% develop hepatocellular carcinoma PiMZ: intermediate plasma levels of AAT Pi-null: rare variant with no detectable serum AAT Pi-S: low serum AAT but no disease

Alpha-1-antitrypsin deficiency AAT deficiency variants: secretory protein does not move from endoplasmic reticulum to GolgiDiagnosis: serum protein electrophoresis; liver biopsy to determine extent of histologic damage Treatment: liver transplantation, Micro: round to oval cytoplasmic eosinophilic globular inclusions in periportal hepatocytes; rare Mallory bodies and fatty change; also hepatocellular degeneration, giant cell formation, cholestasis and cholangitis, portal fibrosis and cirrhosis Positive stains: AAT immunostains; inclusions are strongly PAS+ and diastase resistant EM: granular material in dilated endoplasmic reticulum

The periportal red hyaline globules seen here with periodic acid-Schiff (PAS) stain are characteristic for alpha-1-antitrypsin (AAT) deficiency.

Cystic fibrosis Most common lethal genetic disease in US of whites - affects 1 per 2000-4500 newborns 1 in 20 in US are carriers; most common mutation is #708 of protein that regulates chloride ion transport on Ch 7 (seen in 70% with disease) Mutations cause reduced chloride ion in secretions, thicker respiratory secretions, upper respiratory infections, late pancreatic insufficiency; also cause defective cilia and infertility, meconium ileus (5-10%), intussusception May present as neonatal cholestasis, although most patients have no clinical evidence of liver disease Micro: macrovesicular steatosis, focal biliary cirrhosis (focal findings of inspissated granular eosinophilic material within portal bile ductules, chronic inflammatory infiltrate in portal tract, bile duct proliferation), cirrhosis (10% by age 25)

Hemochromatosis Excessive accumulation of iron, usually deposited in liver, pancreas and heart Either primary or secondary Normal iron pool is 2-6 gm with 0.5 g in liver and 98% of that in hepatocytes   Primary hemochromatosis Autosomal recessive disorder of excessive iron storage; may exceed 50g in liver (normal 2-6 g) Most common single-gene disorder in whites, 80 % males Mutation on transferrin receptor binding protein HFE on 6p Common mutation (83% of primary cases) is cysteine to tyrosine at amino acid 282 (C282Y), which inactivates the protein and causes excess iron absorption of 3-4 mg/day vs. 1-2 mg/day normal; Normal HFE down regulates transferrin; loss of HFE causes up regulation of transferrin. Excessive iron is directly toxic, due to lipid peroxidation, stimulation of collagen, interactions of iron with DNA

Hemochromatosis Symptoms: after accumulation of 20 g of iron; usually age 40+; primarily micronodular cirrhosis diabetes mellitus and skin pigmentation; also hemosiderin deposition in myocardium, pituitary, adrenal, thyroid, parathyroid gland, joints, skin; eventually cirrhosis and pancreatic fibrosis; High risk for hepatocellular carcinoma Gross: dark brown liver

The dark brown color of the liver, as well as the pancreas (bottom center) and lymph nodes (bottom right) on sectioning is due to extensive iron deposition in a middle-aged man with hereditary hemochromatosis

The hepatocytes and Kupffer cells here are full of granular brown deposits of hemosiderin from accumulation of excess iron in the liver.

A Prussian blue iron stain demonstrates the blue granules of hemosiderin in hepatocytes and Kupffer cells. Note that there is also cirrhosis. Excessive iron deposition in persons with HH can affect many organs, but heart (congestive failure), pancreas (diabetes mellitus), liver (cirrhosis and hepatic failure), and joints (arthritis) are the most severely affected.

Wilson’s Disease (Hepatolenticular degeneration) Autosomal recessive disorder causing accumulation of toxic levels of copper in tissues/organs, usually liver, brain, eye The gene for Wilson’s disease is ATP7B on Ch 13q, which encodes a transmembrane copper-transporting ATPase which assists with copper excretion into bile; copper accumulates within the liver causing liver injury By age 5 years, nonceruloplasmin-bound copper causes acute or chronic liver disease, hemolytic anemia, deposition in putamen with frank psychosis or Parkinsonian symptoms, deposition in cornea, kidneys, bones, joints, parathyroid gland; also increased urinary excretion of copper (which is normally minimal) Treatment: long-term copper chelation therapy with D-penicillamine; liver transplantation Micro: liver - fatty change with vacuolated nucleus (due to glycogen or water), focal hepatocyte necrosis; an acute or chronic hepatitis;chronic hepatitis may have Mallory bodies; cirrhosis develops Fulminant hepatitis: liver collapse with abundant lipofuscin due to degraded membrane fragments; remaining liver shows low-grade disease with fibrosis brain - injury to putamen in basal ganglia eye - Kayser-Fleischer rings (green to brown deposits of copper in Descemet’s membrane in limbus of cornea)

Rhodanine stain for copper

Viral Hepatitis:Acute Hepatotropic viruses(A,B,C,D,E and G), EBV,CMV,HSV, yellow fever, HIV In children: rubella, adenovirus,enterovirus Phases: incubation, symptomatic preicteric, symptomatic icteric, convalescence Micro: irregular hepatic plates due to variability in hepatocyte size and inflammatory cells; hepatocyte necrosis portal and lobular lymphocytic inflammation and regenerative activity; hepatocyte death via apoptosis ballooning degeneration or cytolysis (collapse of reticulin network where cells have disappeared with appearance of lymphocytes or macrophages) infiltrate is usually lymphocytes, most prominent in lobules, then spills over into periportal hepatocytes (interface hepatitis) in resolving phase, portal lymphocytes and plasma cells are present with minimal lobular inflammation Kupffer cells contain hemosiderin and lipofuscin

Grossly, there are areas of necrosis and collapse of liver lobules seen here as ill-defined areas that are pale yellow.

At high magnification, the hypercellularity in acute viral hepatitis is noted to be due to infiltration of the hepatic sinusoids by an acute, as well as chronic, inflammatory cellular infiltrate and Kupffer cell hypertrophy and hyperplasia. The hepatic cords are also disrupted with evidence of both hepatocyte necrosis and ongoing hepatocyte regeneration. Regenerating hepatocytes are large, frequently containing multiple nuclei.  

A large pink cell undergoing "ballooning degeneration" is seen below the right arrow. At a later stage, a dying hepatocyte is seen shrinking down to form an eosinophilic "councilman body" below the arrow on the left.

Chronic Viral Hepatitis Diagnosis requires symptomatic, serologic or biochemical evidence of continuing or relapsing hepatic disease of 6 months or more, with histologically documented necrosis and inflammation Etiology (hepatitis C > hepatitis B) is the most important predictive factor for chronic hepatitis; clinical features are not predictive Symptoms: spider angiomas, palmar erythema, mild hepatosplenomegaly, hepatic tenderness, increased prothrombin time and partial thromboplastin time, vasculitis due to immune complex deposition (HBV, HCV), glomerulonephritis, cryoglobulinemia (35% of HCV) Micro: predominantly lymphocytic portal infiltrate with less lobular involvement than acute hepatitis; may have piecemeal necrosis and fibrosis

In this image of liver from a patient with chronic hepatitis due to hepatitis B virus, a chronic inflammatory infiltrate is seen that is limited to the portal area. It does not extend into the adjacent lobule

Chronic hepatitis - grading / staging Grade: degree of inflammation, piecemeal or bridging necrosis Grade 0:  no / minimal inflammation Grade 1:  portal inflammation or lobular inflammation without necrosis Grade 2:  mild periportal inflammation and piecemeal necrosis or focal hepatocellular necrosis Grade 3:  moderate periportal inflammation and piecemeal necrosis or severe focal cell damage Grade 4:  severe periportal inflammation and piecemeal necrosis or bridging necrosis   Stage: degree of fibrosis Stage 0:  no fibrosis Stage 1:  enlarged fibrotic portal tracts Stage 2:  periportal fibrosis or portal to portal septa, without architectural distortion Stage 3:  bridging fibrosis with architectural distortion, no obvious cirrhosis Stage 4:  cirrhosis (probable or definite)

CMV hepatitis: hepatocytes with large, eosinophilic to amphophilic nuclear inclusions surrounded by a clear halo, and cytoplasmic inclusions consisting of basophilic dots (inclusions are viral particles).

Infectious (non-viral) disorders Aspergillus (straight septate hyphal forms with acute angle branching)

Blastomycosis Broad based budding organisms

Coccidiodomycosis Small spherical endospores are present within the large sphere.

Cryptococcus Yeast with thick gelatinous capsule

Echinococcus

Daughter cysts with germinal layer and scolices

Entamoeba histolytica

Entamoeba histolytica peripheral trophozoites up to 60 microns with small eccentric nucleus and cytoplasmic vacuoles that may contain red blood cells; resemble histiocytes; adjacent liver has fibrosis, chronic inflammation and reactive hepatocytes

Alcoholic hepatitis and alcoholic liver disease Alcohol related liver disease consists of hepatic steatosis (50%), alcoholic hepatitis (20%) and cirrhosis (10 Alcoholic cirrhosis: only 10% of alcoholics develop cirrhosis Gross: initially liver is 4-6 kg, yellow, greasy, easily fractured; later liver becomes red with bile-stained areas; may contain visible nodules and fibrosis Micro: steatosis - hepatocyte swelling and necrosis, macrovesicular fatty change due to triglyceride in centrilobular area, Mallory’s hyaline with surrounding neutrophils hepatitis- hepatocyte swelling and necrosis,cholestasis, Mallory bodies, neutrophilic reaction, fibrosis cirrhosis –final and irreversible form of alcoholic liver disease; initially cirrhotic liver is yellow, fatty, enlarged (> 2 kg); eventually becomes brown, shrunken, nonfatty, < 1 kg; initial fibrous septa are delicate, regenerative micronodules; nodules then become larger and have hobnail appearance on hepatic surface, and bands of fibrous tissue become wider. macro- and micronodules

In alcoholic steatosis: lipid accumulates within the cytoplasm of hepatocytes, creating large clear vacuoles within cells. The nuclei in such cells are compressed to the periphery of the cell.   

Alcoholic hepatitis:Mallory's hyaline is seen here, but there are also neutrophils, necrosis of hepatocytes, collagen deposition, and fatty change.

This liver, a case of alcoholic cirrhosis, contains numerous, fairly uniform, small nodules of regenerative hepatocytes separated by depressed areas of fibrous scar tissue. This morphologic pattern is sometimes referred to as micronodular cirrhosis.  

In alcoholic cirrhosis, nodules of regenerating hepatocytes consist of disordered cords of cells of irregular thickness, many of which are two or more cell layers thick. Note the lack of central veins in these regenerative nodules. The nodules are surrounded by fibrous tissue containing variable amounts of chronic inflammatory cells and areas of bile ductular proliferation.     

Biliary Tract Disease Ascending cholangitis Autoimmune cholangitis Primary biliary cirrhosis Primary sclerosing cholangitis Oriental cholangiohepatitis Secondary biliary cirrhosis

Ascending cholangitis Biliary tract infection (E. coli, enterococci) with obstruction Micro: neutrophils within lumina of interlobular bile ducts; large ducts may be destroyed and replaced by scar or atretic ducts

Primary sclerosing cholangitis 65% men, usually under 45 years Possibly autoimmune, 50-70% also have inflammatory bowel disease (particularly ulcerative colitis, although only 4% with ulcerative colitis have primary sclerosing cholangitis) Secondary sclerosing cholangitis: due to stones, prior surgery Symptoms: fatigue, pruritis, jaundice, right upper quadrant pain / tenderness Increased risk for cholangiocarcinoma Xray: beading of barium column in cholangiogram due to irregular strictures and dilations of affected bile ducts Treatment: liver transplant since no effective medical therapy (associated with autoimmune liver disease in 42% and recurrence in 33%) Gross: periductal portal tract fibrosis, segmental stenosis of extrahepatic and intrahepatic bile ducts

Microscopically, this bile duct in a case of sclerosing cholangitis is surrounded by marked collagenous connective tissue deposition(onion-skin concentric scar).

Primary biliary cirrhosis Chronic, progressive, often fatal cholestatic liver disease with destruction of small, intrahepatic bile ducts, portal inflammation and scarring leading to cirrhosis and liver failure Possibly autoimmune; associated with Sjogren’s syndrome, scleroderma, thyroiditis, rheumatoid arthritis, Raynaud’s phenomenon, membranous glomerulonephritis, systemic lupus erythematosus, celiac disease Involves most proximal portion of biliary tree, the small bile ducts and canals of Hering; larger bile ducts affected only irregularly, 85% women, usually ages 40-60

Primary biliary cirrhosis IgM antimitochondrial autoantibodies in 95% 5% - negative antimitochondrial antibody (must have a cholangiogram to rule out primary sclerosing cholangitis) M2 form of anti-mitochondrial antibody, present in 90%, is against E2 subunit of pyruvate dehydrogenase complex–dihydrolipoamide acetyltransferase on inner face of inner mitochondrial membrane, causes hypocomplementemia and formation of immune complexes Antimitochondrial antibodies are most important diagnostic marker; has coarse granular cytoplasmic staining of distal renal tubules and parietal cells (rodent stomach/kidney blocks) with indirect immunofluorescence

The cut surface is dark green, due to marked cholestasis within the liver. Regenerative nodules of liver parenchyma are separated by tan bands of fibrous tissue.     

At higher magnification, it is apparent that the chronic inflammation in the portal areas is associated with bile duct destruction by the inflammatory infiltrate. These are the hallmarks of the florid duct lesions in primary biliary cirrhosis

This immunofluorescence pattern is positive for anti-mitochondrial antibody (AMA) which has an association with primary biliary cirrhosis. The tissue substrate for this test is renal parenchyma, and the tubule cells have lots of mitochondria, which stain bright green.