Hepatic Schistosomiasis

 Periportal fibrotic bands and widened fissures


image Capsular calcification (parallel or perpendicular to liver surface)


• Portal hypertension in advanced disease
image Splenomegaly and varices

• US: Bull’s-eye lesion: Represents anechoic portal vein surrounded by echogenic mantle of fibrous tissue
image Hyperechoic and thickened walls of portal venules

image Network of echogenic septa outlining polygonal areas of normal-appearing liver

• US elastography demonstrates hepatic fibrosis

• MR shows same morphologic signs as CT of liver damage and portal hypertension
image MR elastography provides a measure of extent of hepatic fibrosis, which may determine therapy and prognosis




TOP DIFFERENTIAL DIAGNOSES




• Hepatic cirrhosis
image Often has widened fissures but not as much periportal fibrosis or calcification as with schistosomiasis


CLINICAL ISSUES




• Most common cause of hepatic fibrosis in the world
image Over 200,000,000 persons, mostly in tropics

• Different Schistosoma species affect urinary tract more than liver

• Oral praziquantel for treatment


DIAGNOSTIC CHECKLIST




• Exclude other causes of hepatic fibrosis or cirrhosis

• Hepatic mosaic “tortoise shell” pattern of fibrosis and calcification

image
(Left) Graphic shows striking periportal edema and fibrosis with widened fissures between hepatic segments.


image
(Right) Axial CT shows signs of portal hypertension, including large varices image and splenomegaly. Note the extraordinarily widened hepatic fissures deeply dividing the segments of the liver along the portal vein branches. This is a characteristic feature of hepatic schistosomiasis; the appearance of the liver has been described as that of a tortoise shell.

image
(Left) In low-power micropathology, portal tracts show chronic inflammation, luminal narrowing, and several granulomas containing degenerated Schistosoma ova image. (Courtesy J. Misdraji, MD.)


image
(Right) Axial NECT of the liver shows extensive calcification and peripheral fibrosis in patterns such as thin curvilinear image, subcapsular band-like image, and confluent image. The predominantly peripheral location and calcification of the fibrotic regions are distinguishing features from viral or alcoholic cirrhosis.


TERMINOLOGY


Synonyms




• Bilharzia, bilharziasis, blood fluke


Definitions




• Hepatic parasitic infestation by Schistosoma species


IMAGING


General Features




• Best diagnostic clue
image Periportal fibrotic bands and widened fissures with calcification

• Location
image Diffuse throughout liver

• Morphology
image Distortion of liver architecture and surface contour by extension of periportal fibrosis


CT Findings




• CECT
image Hepatic involvement
– “Tortoise shell” or “turtle back” appearance
image Represents calcified septa, aligned along and perpendicular to liver capsule

– Capsular calcification

– Markedly dysmorphic liver with peripheral atrophy, caudate hypertrophy

– Periportal edema, fibrosis, volume loss

– Splenomegaly and varices

image Colonic involvement
– Ulceration of mucosa

– Submucosal edema + fibrosis

– May progress to calcification of colonic wall


MR Findings




• Shows same morphologic signs as CT of liver damage and portal hypertension

• MR elastography provides a measure of extent of hepatic fibrosis, which may determine therapy and prognosis


Ultrasonographic Findings




• Grayscale ultrasound
image Hepatomegaly in early stages

image Atrophic liver in late stage (fibrosis and portal hypertension)

image Irregular/notched liver surface

image Echogenic granulomata
– Peripheral/subcapsular location

– Egg deposited in terminal portal venule, resulting in inflammatory reaction

image Periportal fibrosis
– Most severe at porta hepatis

– Widened portal tracts

– Hyperechoic & thickened walls of portal veins

– Described as “clay-pipestem” fibrosis

– Bull’s-eye lesion: Represents anechoic portal vein surrounded by echogenic mantle of fibrous tissue

image 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)

image Hyperechoic gallbladder bed

image Associated signs of portal hypertension
– Portal vein dilation

– Varices (gastric/esophageal), ascites, splenomegaly

image Cirrhosis in late stage

image Involvement of urinary tract
– Bladder and ureteric wall irregularities ± calcification

– Fibrotic bladder, ureteric strictures

– Vesicoureteric reflux

– Ureteritis cystica

– Hydronephrosis, hydroureter

image Involvement of gastrointestinal tract
– Polypoid bowel mass

– Bowel strictures

– Granulomatous colitis with calcification

image Elastography demonstrates hepatic fibrosis


Imaging Recommendations




• Best imaging tool
image Ultrasound & CT or MR for diagnosis and follow-up


DIFFERENTIAL DIAGNOSIS


Hepatic Cirrhosis




• Hepatic schistosomiasis may cause or simulate cirrhosis from other causes
image Postnecrotic, alcoholic, etc.

• Cirrhosis often has widened fissures but not as much periportal edema and fibrosis as with schistosomiasis

Nov 16, 2016 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Hepatic Schistosomiasis
Premium Wordpress Themes by UFO Themes