Digestive Pathology Lecture 5

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The liver II

7. Infectious hepatitis

– Bacterial

– Fungal

– Parasitic

– Liver abscess

– Viral8. Non-infectious hepatitis

Bacterial

Hepatitis

– Systemic infections and sepsis

– Some infections are particularly prone to involve the liver (typhoid and paratyphoid)

Pyogenic abscess

Granulomas and granuloma-like lesions

– Tuberculosis, leprosy, syphilis

Peliosis hepatis

– Focal sinusoidal rupture, blood filled cystic spaces

– Bartonella infections (bacillary peliosis), in children, HIV-infected, other immunosuppressed individuals

Peliosis hepatis

Scheuer’s Liver Biopsy Interpretation

Fungal

Mostly in immunocompromised patients

– Candida (the most common)

Parasitic

Malaria

Trematodes– Opisthorchiasis

– Clonorchiasis

– Fascioliasis

– other

Echinococcosis– Cystic (hydatid cyst, Echinococcus granularis)

– Alveolar (Echinococcus multilocularis)

Amebiasis

Liver flukes1. Opisthorchis viverrini

2. Clonorchis sinensis

3. Fasciola hepaticaAC=acetabulum (ventral sucker), CE=cecum, CL=collar, CS=cirrus sac, EB=excretory bladder, EG=eggs (within uterus), ES=esophagus, IN=intestine, OS=oral sucker, OV=ovary, PH=pharynx, SR=seminal receptacle, TE=testes, UT=uterus, VT=vitellaria

Fasciola hepatica

Adult liver flukes, released on incision of the main bile duct in an infected sheep’s liver during a post-mortem examination, www.afbini.gov.uk

Echinococcus granulosusHydatid cyst with daughter cysts

Echinococcus multilocularisAlveolar echinococcosis

www.parasite-diagnosis.ch

Abscesses, etiology

Pyogenic (enterobacteriaceae)

Fungal (C. albicans)

Parasitic (amebic)

Mixed

Liver abscess, routes

Biliary tract (ascending cholangitis), the most common

Hepatic artery (sepsis)

Portal vein (pylephlebitis)

Direct extension (neighboring tissues)

Penetrating injuries

Liver abscess, multiplicity

Solitary abscess: direct extension, penetrating injury

Multiple, small abscesses: biliary, arterial, portal

Pyogenic abscesses, ascending cholangitis

Amebic abscess

Anchovy paste-like necrotic contents with nuclear debris and few inflammatory cells; organisms present at the advancing edge. Odze, Surgical Pathology of the GI Tract, Liver, Biliary Tract and Pancreas

Amebic Liver AbscessPortal route, solitary

CT scan demonstrating a large abscess in the right hepatic lobe. Wells, Christopher D.; Arguedas, Miguel. Southern Medical Journal. 97(7):673-682, July 2004

Liver abscess, complications

Rupture into the abdominal cavity: peritonitis, peritoneal abscesses

Rupture into the thoracic cavity: empyema, lung abscesses

Rupture into the pericardial cavity

High mortality

Viral hepatitis

Systemic infections (secondary /non-hepatotropic)

– Yellow fever, in tropical regions

– Mononucleosis (Epstein-Barr Virus)

– In children and immunosuppressed:

• Cytomegalovirus

• Herpesvirus

• Adenovirus

• Other

Primary /hepatotropic viruses

Hepatotropic viruses

Hepatitis A, B, C, D, E

Enveloped and un-enveloped

Enveloped viruses (B, C and D)

Wrap themselves with a lipid bilayer that they adopt from infected cells

Enveloped viruses (B, C and D)

Sensitive to desiccation, detergents

Susceptible to emulsification by bile acids

Do not survive in feces

Not specialized in fecal-oral transmission

Transmission by contact with body fluids– Percutaneous

– Mucosal, sexual

– Vertical (mother to fetus, perinatal)

Long incubations, persistent viremia

Enveloped viruses (B, C, D)

Cause carrier state– Persistent infection with no signs or

symptoms of disease

Cause chronic hepatitis– Evidence of disease > 6 months

Linked to cirrhosis, hepatocellular carcinoma

Immune complex deposition– Arthralgias, vasculitis, glomerulonephritis

Unenveloped viruses (A and E)

Not wrapped in lipid bilayer

Survive exposure to bile

Specialized in fecal-oral transmission

Short incubation periods

Short-lasting viremia

Rare bloodborne transmission

No chronic hepatitis, no carrier state in immunocompetent individuals

Not linked to hepatocellular carcinoma

Hepatitis A Single stranded RNA

Incubation 2-6 weeks

Prodromal (pre-icteric) state

Icteric state

May be anicteric

May be subclinical, particularly in young children

May be fulminant

Shed in feces 2-3 w before to 1 w after jaundice

Shellfish concentrate the virus

Contaminated agricultural products cause outbreaks

Hepatitis A Sexual transmission may occur

Bloodborne transmission may occur

May follow a prolonged course

May relapse

Rare reports of chronic hepatitis

Hepatitis A

Diagnosis:

– Acute hepatitis:

• IgM anti-HAV, blood

• HAV RNA, feces

– Previous exposure: IgG (total) anti-HAV, protective immunity

Vaccine available since 1995

Hepatitis A incidenceVaccine licensed in 1995

Hepatitis A incidence

Rate per 100,000 population by county before and after widespread use of vaccination. National Notifiable Disease Surveillance System

Hepatitis E

Single-stranded RNA

Incubation 2-9 weeks

Enzootic/zoonotic (cows, pigs, sheep, goats, rodents, deer, wild boars…)

In developing countries:– Genotypes 1 and 2

– Mostly young and middle age adults

– May be subclinical in children

– Pregnant women, third trimester, mortality 20-30%

Geographic distribution of hepatitis E

Chronic hepatitis E

Chronic infection that may progress to cirrhosis has been reported in:

– Immunosuppressed patients (particularly organ transplant recipients)

– HIV-infected individuals

Hepatitis E

Diagnosis:

– Acute hepatitis

• IgM anti-HEV, blood

• HEV RNA, feces

– Previous exposure: IgG anti-HEV, loss of antibodies over time, re-infections may occur

Vaccine is available since 2012 (China)

Hepatitis E indigenous to developed countries

Genotypes 3 and 4

Among healthy individuals seroprevalence 5-20%

Clinical disease in middle age and older individuals

Severity increases with age

Pet ownership or occupational exposure to pigs

Uncooked, undercooked meat or viscera: pigs, deer, boars

New Microbiologica, 36, 331-344, 2013

Hepatitis E, genotypes

Tatsuo Miyamura. Hepatitis E virus infection in developed countries. Virus Research Volume 161, Issue 1 2011 40 – 46. http://dx.doi.org/10.1016/j.virusres.2011.03.006

Food source of infection of domestic hepatitis E cases, Japan, 2009

Hepatitis B

Double stranded DNA virus

Incubation 4-26 weeks

Acute illness may be subclinical or have symptoms similar to hepatitis A– Jaundice occurs less often

May be fulminant

May resolve completely

May become chronic:– Asymptomatic (carrier state)

– Symptomatic

Hepatitis B outcome

Hepatitis B, risk factors

Sex with an infected partner, sexual promiscuity

Injection drug use sharing needles, syringes

Birth to an infected mother

Contact with blood or fluids of an infected person

Needle sticks or sharp instrument exposures

Sharing razors or toothbrushes

Tattooing, body piercing

Inmates, institutional overcrowding

Hepatitis B, risk of chronicity Newborn (vertical transmission), 90% < 1, 70-90% 2-3, 40-70% 4-6, 10-40% >7, 6-10% Immunocompetent adult, <5% Immunocompromised adult, >50% Dominant cause of viral persistence:

– Weak immune response– Tolerance

Recombinant vaccine

HBV virion (Dane particle)

– Surface antigen, envelope, HBsAg

– “Core" antigen, nucleocapsid, HBcAg

– Non-structural "e" antigen, HBeAg

– HBx protein (replication, trans-activate host genes)

– DNA polymerase

– HVB DNA

Hepatitis B, surface antigen

Hepatitis Web StudyUniversity of Washington

Hepatitis B, phases

Proliferative (episomal)

– Formation of complete virions

Integrated

– Virus integrated into the host’s DNA

– Cessation of viral replication

– Continuous production of HBsAg

Hepatitis B, pathogenesis

Expression of HBsAg and HBcAg on hepatocytes activates cytotoxic T lymphocytes, responsible for the cell damage

Immunosuppressed individuals suffer less cell damage but are more likely to develop chronicity

Chronic cell injury, inflammatory and regenerative responses promote carcinogenesis

Hepatitis B, diagnosis Acute infection

– HBsAg

– IgM anti-HBcAg

Active viral replication, infectivity– HBeAg

– HBV DNA

Chronic infection:– > 6 months: HBsAg

– IgM anti-HBcAg has been replaced by IgG anti-HBcAg

Hepatitis B, prior infection, vaccine

Resolution, prior infection

– HBsAg, HBV DNA and HBeAg disappear

– IgG Anti-HBsAg appear and persist

Vaccination effect:

– Anti-HBsAg present without anti-HBcAg

– Vaccine is made of recombinant HBsAg

Hepatitis D (Delta agent)

Very small, single-stranded RNA virus

Replication defective, requires HBsAg

Coinfection– Fulminant disease more likely

– Chronicity <5%

Superinfection of HBV carrier– Fulminant hepatitis less likely

– Chronicity: 80%

In the US mostly restricted to– Drug addicts

– Hemophiliacs

– Their sexual contacts

Prophylaxis: vaccination for HBV, no vaccine for HDV

Wedemeyer, H. & Manns, M. P. (2010) Epidemiology, pathogenesis and management of hepatitis D: update and

challenges ahead. Nat. Rev. Gastroenterol. Hepatol. doi:10.1038/nrgastro.2009.205

Prevalence of HDV infection, viral genotype

Hepatitis D, diagnosis IgM anti-HDV

Coinfection with HBV:

– IgM anti-HDV with HBsAg and IgM anti-HBcAg

Superinfection

– IgM anti-HDV, with HBsAg, without IgM anti-HBcAg

HDV RNA

Immunohistochemistry

Hepatitis C

Single-stranded RNA virus

Classified into six major genotypes

Genotypes 1a and 1b cause 70% of all infections in the US

Hepatitis C, evolutionary treeAmerican Association for the study of liver diseases, 2005

Hepatitis C

Incubation 2 to 26 weeks

Acute infection commonly subclinical

No fulminant presentation

High rate of chronicity, 55-85%

High rate of progression to cirrhosis

High rate of progression to HCC

Natural history of HCV infection

100 People

Resolve (15)

15%

Chronic (85)

85%

Cirrhosis (17)Stable (68)

80%

75%

Stable (13)

Mortality (4)

25%

20%

Hepatitis C, risk factors

Reported risk factors in the US:

– Intravenous drug abuse, 60%

• Highly efficient mode of transmission

– Sexual, < 20%

• Rare between long-term sex partners (1.5-3%)

– Perinatal transmission is low

– Health care workers

• Risk after needle stick accident: (1.8-10%)

– No recognized source of infection 10%

Hepatitis C

HCV genome is unstable• Emergence of mutated strains (quasispecies)

cause recurrences

• Variability hampers development of vaccine

• IgG anti-HCV does not confer protection

• Rapid variation may cause resistance to therapy

– New antiviral therapies promise cure rates >90%

Hepatitis C

Diagnosis:– Antibodies anti-HCV

• Enzyme immunoassay (EIA)

• Recombinant immunoblot assay (RIBA)

• Only total antibodies are measured, IgM anti-HCV is not used (does not indicate acute infection)

• Detectable 7 weeks after exposure, remain positive for life

• Indicate exposure to the virus not current infection

Hepatitis C

Diagnosis:– HCV RNA

• Qualitative

• Quantitative

• Detectable 2 weeks after exposure

Hepatitis G

GB virus type C (GBV-C)

RNA virus, flavivirus, same family as hepatitis C, yellow fever and West Nile viruses

Parenteral, sexual, vertical transmission

Transmission by transfusion documented

Lymphotropic, no hepatotropic

Pathogenic capacity questioned

Coinfection with HIV and GBV-C associated with a BETTER outcome for the HIV infection

Acute hepatitis, morphology Centered in the lobules (lobular, lobulocentric)

– More severe in zone 3 than in portal/periportal areas

Inflammation

– May be mostly lymphocytic

Hepatocyte injury

– Ballooning

– Apoptosis

– Necrosis (focal, bridging, submassive or massive)

Hepatocyte regeneration

– Variation in size

– Disarray of liver plates

Acute viral hepatitis

Hepatocytes in the perivenular area in the center of the field are swollen and the area is infiltrated by inflammatory cells. Scheuer’s Liver Biopsy Interpretation.

Chronic hepatitis, histology

Centered in the portal/periportal area

Grade, determined by the extent of:

– Portal/periportal inflammation

– Hepatocyte injury (ballooning, apoptosis, necrosis)

Stage, determined by the extent of fibrosis

– Portal

– Periportal

– Bridging

– Cirrhosis

Chronic hepatitis, grading (interface hepatitis)

Chronic hepatitis, grading (lytic necrosis)

Chronic hepatitis, staging (fibrosis)

HBV, ground-glass hepatocytes

HBV, surface antigen, immunoperoxidase

HVB, sanded nuclei

HBV, core antigen, immunoperoxidase

The liver II7. Infectious hepatitis

Non-infectious hepatitis

8. Autoimmune hepatitis

9. Drug induced

10. Alcoholic and non-alcoholic steatohepatitis

11. Inborn errors of metabolism

• Wilson disease

• Alpha1-antitrypsin deficiency

• Primary biliary cirrhosis

8. Autoimmune hepatitis T-cell mediated injury

Genetic predisposition

May be triggered by viral infections, drugs

Female predominance, >70%

Concurrent autoimmune diseases

Morphologically similar to viral hepatitis– Prominent plasma cell infiltrate

– Tends to be the more severe• Acute presentation is common, may be fulminant

• May progress rapidly to cirrhosis

Responds to immunosuppressive therapy

Autoimmune hepatitisProminent plasma cell infiltration, severe

Autoimmune hepatitis

Elevated serum gamma-globulin

Autoantibodies:

– Type 1, most common

• Anti-nuclear (ANA)

• Anti-smooth muscle (ASMA)

– Type 2, rare, mostly children

• Anti-liver/kidney microsome 1 (LKM1)

• Anti-liver cytosol-1 (ALC1)

Biopsy

9. Drug and toxic liver injury

Direct toxicity

Indirect toxicity, hepatic conversion

Immune injury, usually as a hapten– Small molecule elicits immune response

when attached to a large carrier

Predictable and unpredictable injury

Predictable (intrinsic)– Occur in anyone, at sufficient dose

(acetaminophen)

Unpredictable (idiosyncratic)– Immune response (halothane)

– Slow metabolism (isoniazid)

Macrovesicular steatosis, methotrexate

Ethanol, amiodarone

Microvesicular steatosis, tetracycline

Salicylates (Reye syndrome)

Centrilobular necrosis, carbon tetrachloride

Acetaminophen

Massive necrosis, isoniazid

Acetaminophen, halothane, Amanita phalloides

Chronic hepatitis, nitrofurantoin

Methyldopa, isoniazid, phenytoin, oxyphenisatin

Granulomatous hepatitis, phenylbutazone

Sulfonamides, hydralazine, allopurinol, quinidine

Cholestasis, erythromycin estolate

Chlorpromazine, anabolic steroids, contraceptives

Acetaminophen

Metabolism

– Small amount metabolized by cytochrome P-450 to form toxic oxidative metabolites (particularly N-acetyl-p-benzoquinone imine NAPQI)

– Toxic metabolites are inactivated by glutathione

Acetaminophen toxicity, treatment

Inactivation of toxic metabolites overwhelmed by overdose

Alcohol potentiation

– Induces cytochrome P-450

– Depletes glutathione

Treatment:

– N-acetyl cysteine, restores glutathione

Reye syndrome

Children given aspirin for virus-induced fever (respiratory infections, varicella)

Defect in mitochondrial fatty acid oxidation

Fatty acids accumulate in the SER– Extensive microvesicular steatosis

Liver failure

Hepatic encephalopathy

Potentially fatal

Reye syndrome

10. Steatohepatitis

Alcoholic

Non-alcoholic

Alcoholic liver disease

Leading cause of liver disease

Fifth leading cause of death

25-30% of hospitalized patients

Spectrum of injury:

– Steatosis

– Steatohepatitis

– Established cirrhosis

Alcoholic steatohepatitis, individual susceptibility

Men, significant toxicity at >80 gm/day

Increased susceptibility:– Women

– Asians (slow aldehyde dehydrogenase)

– African Americans

Concomitant iron overload, HBV or HCV infections and other comorbid conditions

Only 10% of alcoholics develop cirrhosis

Ethanol, metabolism

Ethanol

Acetaldehyde

Acetate

NAD

NADH + H

NAD

NADH + H

Alcohol dehydrogenase

Aldehyde dehydrogenase

Alcoholic steatohepatitis, etiology

Induction of cytochrome P-450 (increase in toxic metabolites)

Depletion of glutathione

Generation of free radicals

Acetaldehyde causes lipid peroxidation and protein adduct formation

Release of bacterial endotoxin from the gut

Malnutrition– Alcohol constitutes the major calorie source

– Impaired digestive function

– Pancreatitis

Alcoholic steatohepatitis, etiology

Steatosis

– Shunt metabolism toward lipid biosynthesis

• Alcohol dehydrogenase, aldehyde dehydrogenase generate excess NADH

– Increased peripheral catabolism of fat

– Impaired assembly and secretion of lipoproteins

Alcoholic steatohepatitis

Steatosis, centrilobular

Cell injury

– Ballooning

– Mallory bodies

– Necrosis, apoptosis

Inflammation

Fibrosis, initially centrilobular

Cirrhosis (Laennec)

Alcohol, ballooning, Mallory bodies

Mallory body, satellitosis

Alcohol, perivenular fibrosis, steatosis

Central Venule

Alcohol, perivenular/pericellular fibrosis

Alcohol, perivenular, portal, bridging fibrosis

Non-alcoholic fatty liver disease (NAFLD)

Continuum of steatosis, hepatocyte injury, inflammation, fibrosis and cirrhosis

The designation of non-alcoholic steatohepatitis (NASH) applied when there is evidence of significant hepatocellular injury and inflammation

Non-alcoholic fatty liver disease (NAFLD)

Major risk factors:– Central obesity (visceral adiposity)– Insulin resistance (glucose intolerance)/type 2

diabetes, – Hypertriglyceridemia

Prevalence and severity increase with age Affects between 17 and 30% of Americans Prevalence is highest among Hispanics

Non-alcoholic steatohepatitis (NASH)

Morphologically similar but less severe than alcoholic steatohepatitis

Asymptomatic elevation of aminotransferases

Likelihood of progression to cirrhosis

Pathogenesis of NASH, lipotoxicity

Increased dietary fat and insulin resistance cause an increased influx of FFAs into the liver

FFAs should undergo β-oxidation or must be stored as triglycerides (steatosis)

Oxidation is compromised with insulin resistance

Individuals who develop NASH may have a reduced capacity to store FFAs as triglycerides

When the storage of FFAs is overwhelmed, FFAs generate toxic lipid metabolites that act as ROS resulting in oxidative injury and inflammation

Current concept of steatohepatitis

Insulin resistance; excessive peripheral lipolysis; increased influx of free fatty acids; lipotoxicity, oxidative stress, inflammation, fibrosis in patients who fail to adequately incorporate FFAs into triglycerides; good fat storers have a benign outcome unless additional hepatic injury (second hit) occurs