Schistosomiasis (hepatic manifestations)

Schistosomiasis hepatic manifestations are a chronic result of the deposition of eggs into small portal venules leading to periportal fibrosis and liver cirrhosis.

For a general view over this trematode infection, please refer to the main article on schistosomiasis.

Epidemiology

Associations

Associated with an increased risk of hepatocellular carcinoma, particularly secondary to the S.Mansoni subtype

Clinical presentation

Usually, these patients will present with portal hypertension signs and symptoms, including splenomegaly, gastroesophageal varices, hematemesis, and ascites. Hepatic function is commonly preserved until late stages .

Pathology

Living in the bowel lumen, Schistosomes lay eggs in the mesenteric veins and, thus, these eggs can reach the portal vein. Species S. mansoni and S. japonicum are most common. Within the portal venules, an inflammatory reaction and consequent granulomatous response will lead to periportal fibrosis as a healing process . Due to the difference in the size of the eggs, S. mansoni infection has its eggs deposited along the large portal veins of the hepatic hilum, whereas the S. japonicum infection has the eggs laying within the small peripheral portal veins .

Radiographic features

Imaging manifestations only occur late in the course of the chronic infection and there are some specific features related to the different distribution of the eggs depending on S. mansoni or S. japonicum infection.

Ultrasound

• common features
  • irregular hepatic surface
  • mosaic pattern: echogenic septa outlining polygonal areas of relatively normal liver parenchyma
  • septal fibrosis 
  • splenomegaly
    • splenic siderotic nodules (Gamna–Gandy bodies)
• S. japonicum
  • septa and capsular calcifications 
• S. mansoni
  • portal veins wall thickening and increased echogenicity
    • “bull’s-eye” appearance: an anechoic portal vein surrounded by echogenic fibrous tissue

CT

• common features
  • irregular hepatic contour
  • splenomegaly
    • splenic siderotic nodules (Gamna–Gandy bodies)
• S. japonicum
  • turtle back sign: calcified septa and fibrosis resembling a turtle carapace, considered pathognomonic
  • capsular calcification
  • periportal fat extending deep into the liver due to the parenchymal retraction
• S. mansoni
  • low-attenuation surrounding the portal vein branches associated with marked contrast enhancement (periportal fibrosis)
  • eggs calcification is not seen as commonly as calcification of S.
    japonicum eggs and consequently calcification along the portal tracts is not a common feature