Diagnostic Ultrasound - Abdomen and Pelvis

Hepatic Schistosomiasis
Diagnoses: Liver
TERMINOLOGY
• Hepatic parasitic infestation by Schistosoma species
IMAGING
• CT: "Tortoise shell" or "turtle back" appearance
○ Peripheral periportal fibrosis, widened fissures
○ Capsular calcification (parallel or perpendicular to liver
surface)
• Portal hypertension in advanced disease
○ Splenomegaly and varices
• US: "Bull's-eye" lesion: Represents anechoic portal vein
surrounded by echogenic mantle of fibrous tissue
○ Hyperechoic and thickened walls of portal venules
○ Network of echogenic septa outlining polygonal areas of
normal-appearing liver
TOP DIFFERENTIAL DIAGNOSES
• Hepatic cirrhosis
KEY FACTS
○ Often has widened fissures but periportal fibrosis is
central in distribution (as opposed to peripheral in
hepatic schistosomiasis)
○ Both can be complicated by portal hypertension
CLINICAL ISSUES
• Most common cause of hepatic fibrosis in the world
○ Over 200 million persons, mostly in tropics
• Different Schistosoma species affect urinary tract more than
liver
• Single dose of oral praziquantel cures > 85% of cases
DIAGNOSTIC CHECKLIST
• Exclude other causes of hepatic fibrosis or cirrhosis
• Hepatic mosaic "tortoise shell" pattern of fibrosis and
calcification
(Left) Graphic of hepatic
schistosomiasis shows striking
periportal fibrosis with
widened fissures ſt between
hepatic segments and
lobulated liver contour .
Peripheral periportal fibrosis
leads to a "turtle back"
appearance of the liver.
(Right) Axial NECT of the liver
in a patient with
schistosomiasis shows
predominantly peripheral
calcifications , with some
calcifications perpendicular in
orientation st to the liver
capsule. Note widened fissures
and irregular hepatic
surface.
(Left) Longitudinal ultrasound
demonstrates thickening and
hyperechogenicity at the porta
hepatis ſt consistent with
periportal fibrosis in a patient
with schistosomiasis.
(Courtesy W. Chong, MD.)
(Right) Axial T2WI MR
demonstrates T2-hyperintense
subcapsular st and periportal
fibrotic bands ſt consistent
with periportal fibrosis in a
patient with hepatic
schistosomiasis. Additionally,
splenomegaly indicates
portal hypertension. (Courtesy
W. Chong, MD.)
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