Page 441 - Concise Pathology for Exam Preparation ( PDFDrive )

426 SECTION II Diseases of Organ Systems

Dubin–Johnson Syndrome
• Autosomal recessive inheritance
• Decreased canalicular excretion of bilirubin into biliary canaliculi
• Conjugated hyperbilirubinaemia and bilirubinuria
• The degree of hyperbilirubinaemia may be increased by intercurrent illness, oral contra-
ceptives and pregnancy.
• The syndrome is due to defective MRP2 (multidrug resistance-associated protein 2),
which is required for secretion of conjugated bilirubin from the hepatocytes into
canaliculi.
• BSP (bromsulphthalein) retention test shows impaired clearance with a reflux
back into blood in 90 min.
• Hepatomegaly with a dark pigment in centrilobular hepatocytes (derived from polym-
erized epinephrine metabolites)

Rotor Syndrome
• Autosomal recessive inheritance
• Due to poor uptake and storage of bilirubin by liver cells
• Mild jaundice, conjugated hyperbilirubinaemia and bilirubinuria
• BSP retention test shows impaired clearance but there is no reflux back into blood.
• Liver biopsy is normal and does not show dark pigment.

Q. Outline the aetiology, epidemiology, clinical features and
laboratory diagnosis of viral hepatitis.
Ans. Types of Viral Hepatitis
1. Hepatitis A caused by hepatitis A virus (HAV)
2. Hepatitis B caused by hepatitis B virus (HBV)
3. Delta hepatitis caused by hepatitis D virus (HDV)
4. Hepatitis C caused by hepatitis C virus (HCV)
5. Hepatitis E caused by hepatitis E virus (HEV)
6. Hepatitis G virus
7. Hepatitis caused by other viruses (cytomegalovirus, Epstein–Barr virus, Herpes simplex
virus and yellow fever virus)
1. Hepatitis A
Aetiology
Caused by hepatitis A virus (HAV), an RNA virus belonging to the Picornavirus group
Epidemiology
• Incubation period is 2–6 weeks
• HAV is transmitted almost exclusively by the feco-oral route (infected persons excrete
the viruses in their faeces for two weeks before the onset and one week after the
onset of the illness). Source of the infection is contaminated water, milk and raw or
steamed shell fish.
• Can rarely spread by blood transfusions and homosexual activity
• Does not cause chronic liver disease or carrier state; rarely causes fulminant hepatitis
(0.1% case fatality)
• It is more common in children and rare in adults.
2. Hepatitis B
Aetiology
• Caused by an enveloped DNA virus called hepatitis B virus (HBV), belonging to the
group of hepadnaviruses
• HBV is a 42 nm ‘Dane particle’ composed of
• A surface envelope (antigen expressed on it is called hepatitis B surface antigen,
HBsAg)
• A nucleocapsid core containing DNA (antigen expressed on its surface is called
hepatitis B core antigen or HBcAg)

mebooksfree.com