Acute Viral Hepatitis

 Hepatitis C accounts for ∼ 20% of cases of acute hepatitis

Clinical Issues

• Symptoms generally mild or patients are asymptomatic
image Fulminant hepatic failure is rare
• Most patients with acute hepatitis A virus infection fully recover within 2 months of disease onset
image No specific drug therapy available for acute hepatitis A virus infection
• Laboratory values
image Elevated transaminases at 5-10x normal values
image Viral serologies often helpful
• Supportive care is mainstay of treatment for patients with acute hepatitis A or acute hepatitis E
image Drug therapy (antivirals or immune modulators) may be useful in acute hepatitis B and C

Microscopic

• Lobular disarray characterized by diffuse lobular inflammation and hepatocyte swelling, necrosis, and regeneration
• May see mild portal and periportal inflammation, particularly in acute hepatitis A virus infection

Diagnostic Checklist

• Lobular inflammation and injury exceed portal inflammation
• Usually recognized clinically, so liver biopsy seldom performed
image
Lobular DisarrayThis biopsy shows diffuse lobular disarray characterized by hepatocyte swelling image, single-cell necrosis image, and areas of hepatocyte dropout image in a background of lobular inflammation. The lobule looks disorganized at relatively low power, indicative of the injury to the hepatocytes.

image
Lobular InflammationH&E demonstrates mild hepatocyte swelling image, Kupffer cell hyperplasia image, and lobular inflammation in a case of acute viral hepatitis.
image
Hepatocyte SwellingH&E demonstrates lobular disarray characterized by hepatocyte swelling image, Kupffer cell hyperplasia image, and lobular inflammation in a case of acute viral hepatitis.
image
Lobular DisarrayH&E shows the diffuse hepatocyte swelling and lobular inflammation atypical of acute viral hepatitis. The lobular injury is typically much more prominent than portal inflammation in acute viral hepatitis.

TERMINOLOGY

Definitions

• Hepatocyte necrosis and inflammation resulting from acute viral infection

ETIOLOGY/PATHOGENESIS

Hepatitis A Virus

• Single-stranded RNA virus in Picornaviridae family
• Usually spreads via oral or fecal-oral transmission
image Community outbreaks related to contaminated food or water
• Accounts for ∼ 1/2 of acute viral hepatitis cases in USA
• At least 4 genotypes described, but only 1 serotype exists
image Infection with one genotype confers immunity against all genotypes
• Never results in chronic infection

Hepatitis B Virus

• Partially double-stranded DNA virus in Hepadnaviridae family
• Parenteral, perinatal, and sexual transmission
• Up to 40% of acute hepatitis cases in USA attributable to hepatitis B
• ∼ 10% of infected patients develop chronic infection

Hepatitis C Virus

• RNA virus of Flaviviridae family
• Parenteral, perinatal, and sexual transmission
• Accounts for ∼ 20% of cases of acute hepatitis
• Only 10-15% of infected individuals develop symptomatic acute hepatitis
• If untreated, ∼ 85% of infected patients develop chronic infection

Hepatitis D Virus (Delta Agent)

• Defective RNA virus
• Parenteral and sexual transmission
• Requires coinfection with hepatitis B virus or superinfection in patient with chronic hepatitis B virus infection

Hepatitis E Virus

• Single-stranded, nonenveloped RNA virus in Caliciviridae family
• 4 routes of infection
image Vertical transmission
image Parenteral transmission
image Consumption of raw or undercooked meat of infected animals
image Contaminated water supply
• Endemic in parts of Asia, Africa, and India

Other Viruses

• CMV
• Epstein-Barr virus

CLINICAL ISSUES

Presentation

• Nonspecific systemic symptoms: Malaise, fatigue, nausea, vomiting, anorexia, low-grade fever, right upper quadrant pain

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Apr 20, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Acute Viral Hepatitis

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