Diagnostic Ultrasound - Abdomen and Pelvis

Hepatic Schistosomiasis
TERMINOLOGY
Synonyms
• Bilharzia, blood fluke
Definitions
• Hepatic parasitic infestation by Schistosoma species
IMAGING
General Features
• Morphology
○ Distortion of liver architecture and surface contour by
extension of periportal fibrosis
○ Most common cause of hepatic fibrosis worldwide
• Periportal fibrotic bands and widened fissures with
calcification
Ultrasonographic Findings
• Grayscale ultrasound
○ Atrophic liver in late stage (fibrosis and portal
hypertension)
○ Irregular/notched liver surface
○ Echogenic granulomata
– Peripheral/subcapsular location
○ Periportal fibrosis
– Most severe at porta hepatis
– Widened portal tracts
– Hyperechoic & thickened walls of portal veins
– "Bull's-eye" lesion: Represents anechoic portal vein
surrounded by echogenic mantle of fibrous tissue
○ Mosaic pattern
– Network of echogenic septa outlining polygonal areas
of normal-appearing liver
– Represents complete septal fibrosis (inflammation
and fibrosis as reaction to embolized eggs)
CT Findings
• CECT
○ "Tortoise shell" or "turtle back" appearance
– Represents calcified septa, usually aligned
perpendicular to liver capsule
○ Capsular calcification
○ Junctional notches or depressions, irregular hepatic
contour
○ Dysmorphic liver with peripheral atrophy, caudate
hypertrophy
○ Periportal edema, periportal fat, fibrosis, volume loss
○ Splenomegaly and varices
Imaging Recommendations
• Best imaging tool
○ Ultrasound &/or CT for diagnosis and follow-up
DIFFERENTIAL DIAGNOSIS
Hepatic Cirrhosis
• Hepatic schistosomiasis may cause or simulate cirrhosis
from other causes
• Cirrhosis often has widened fissures but not as much
periportal edema & fibrosis as with schistosomiasis
PATHOLOGY
General Features
• Etiology
○ Caused by parasites that live in certain freshwater snails
○ S. japonicum: North Asia
○ S. mansoni: Africa, Egypt, Caribbean, South America
– Causes most severe disease in liver
○ S. hematobium: Mediterranean, Africa, Southeast Asia
– Typically affects urinary tract
• Associated abnormalities
○ May involve urinary system
– Thickened bladder wall ± calcification
Gross Pathologic & Surgical Features
• Adult worms live in pairs within portal veins for years
○ S. japonicum in superior mesenteric vein (SMV); S.
mansoni in inferior mesenteric vein (IMV)
○ S. hematobium: Bladder and ureteric veins
• Female worm releases eggs, which travel in blood to
become trapped in tissues of different organs
• Trapped eggs stimulate granulomatous reaction, which is
reversible in early stages but becomes fibrotic later
• Fibrosis may lead to organ damage
○ Liver: Periportal fibrosis, portal hypertension,
gastrointestinal hemorrhage
○ Urinary tract: Obstructive uropathy (renal failure),
pyelonephritis, glomerulonephritis, amyloidosis
Microscopic Features
• Multiple tiny granulomas scattered in periphery of liver
• Granuloma consists of egg in center surrounded by
macrophages, lymphocytes, neutrophils, and eosinophils
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Acute infection: Dermatitis, fever, hepatomegaly
• Clinical profile
○ Eosinophilia (may be absent in chronic disease)
○ Living eggs in stool/urine (need to perform egg viability
test)
○ Antibody specific to Schistosoma
Treatment
• Single dose of oral praziquantel cures > 85% of cases
○ 2nd dose needed if viable eggs in stool or urine 6-12
weeks after initial treatment
SELECTED REFERENCES
1. Lambertucci JR: Revisiting the concept of hepatosplenic schistosomiasis and
its challenges using traditional and new tools. Rev Soc Bras Med Trop.
47(2):130-6, 2014
2. Ma C et al: Histopathologic evaluation of liver biopsy for cirrhosis. Adv Anat
Pathol. 19(4):220-30, 2012
3. MacConnachie A: Schistosomiasis. J R Coll Physicians Edinb. 42(1):47-9; quiz
50, 2012
4. Silva LC et al: Ultrasound and magnetic resonance imaging findings in
Schistosomiasis mansoni: expanded gallbladder fossa and fatty hilum signs.
Rev Soc Bras Med Trop. 45(4):500-4, 2012
5. Strahan R et al: Ultrasound study of liver disease caused by Schistosoma
mansoni in rural Zambian schoolchildren. J Med Imaging Radiat Oncol.
56(4):390-7, 2012
http://radiologyebook.com/
Diagnoses: Liver
191