Diagnostic Ultrasound - Abdomen and Pelvis

Biliary Hamartoma
TERMINOLOGY
Synonyms
• von Meyenburg complex, bile duct hamartoma
Definitions
• Benign malformations of biliary tract
IMAGING
General Features
• Best diagnostic clue:Numerous small cystic lesions < 1.5 cm
in diameter throughout whole liver
• Location: Subcapsular or intraparenchymal location
• Size:0.2-1.5 cm (rarely larger)
• Morphology
○ Typicallywell circumscribed but not encapsulated
○ Multiple lesions much more common, rarely solitary
Ultrasonographic Findings
• Grayscale ultrasound
○ Numerous small, hypo-/hyperechoic foci uniformly
distributed throughout liver
– When small, appear hyperechoic due to inability to
resolve tiny cysts
– Appear cystic when > 2-3 mm
– Leads to inhomogeneous and coarse appearance of
liver echotexture
○ Multiple echogenic foci:May see associated "comet tail"
artifacts
○ Liver often more echogenic with fewer cystic lesions
than anticipated based on prior CT or MR due to cystic
lesions being too small to resolve internal cystic space
• Color Doppler
○ May see twinkling artifact
– Rapidly alternating red and blue color Doppler signal
behind echogenic foci
– Thought to be related to multiple reverberations from
cholesterol crystals within cystic dilatation of bile
ducts
CT Findings
• CECT
○ Solid components (fibrous stroma) can enhance and may
become nearly isodense to liver
○ Multiple small, round, and well-defined nodules of low
attenuation without enhancement
MR Findings
• T1WI: Low signal;T2WI: High signal due to fluid content
• T1WI C+: Usually no enhancement, but thin rim
enhancement reported related to compressedliver
parenchyma surrounding biliary hamartoma
• MRCP: Numerous tiny cysts without communication with
biliary tree
Imaging Recommendations
• Best imaging tool
○ Ultrasound with grayscale and color Doppler
○ MRCP/heavily T2WI
DIFFERENTIAL DIAGNOSIS
Multiple Simple Hepatic Cysts
• Rarely as numerous as biliary hamartomas
• Regularly outlined and no contrast enhancement
Multiple Small Hepatic Metastasis
• More varied in size and distribution
• More mural nodularity and complexity, rim enhancement
Hepatic Microabscesses
• Enhancing wall, double target sign can be seen
• In immunosuppressed patient with fever
Autosomal Dominant Polycystic Liver Disease
• Usually larger cysts, and coexisting cysts in kidneys and
other organs
Caroli Disease
• Small, round/saccular dilatations of intrahepatic ducts
• "Central dot" sign on US, CECT, and MR
○ Enhancing tiny dots (portal radicles) within dilated IHD
PATHOLOGY
General Features
• Etiology
○ Congenital ductal plate malformation due to failure of
involution of embryonic bile ducts
○ May coexist with autosomal dominant polycystic kidney
disease (APDKD), Caroli disease, congenital hepatic
fibrosis, bile duct atresia, or choledochal cyst
Microscopic Features
• Noncommunicating bile ducts interspersed within
hyalinized fibrocollagenous stroma; may contain
proteinaceous debris or bile
CLINICAL ISSUES
Presentation
• Asymptomatic and of no clinical concern
Demographics
• Detected incidentally at autopsy in 0.6-5.6% of cases
DIAGNOSTIC CHECKLIST
Consider
• May be misdiagnosed as multiple hepatic metastases,
microabscesses, cirrhosis, lymphoma, leukemia, etc. at initial
imaging
• No further evaluation necessary when seen as isolated
finding in healthy, nononcologic patient
Image Interpretation Pearls
• In setting of numerous small cysts in healthy patients
• Ultrasound: Numerous echogenic foci often with
accompanying "comet tail" artifacts throughout whole liver;
may see associated color Doppler twinkling artifact
SELECTED REFERENCES
Diagnoses: Liver
http://radiologyebook.com/
1. Vachha B et al: Cystic lesions of the liver. AJR Am J Roentgenol.
196(4):W355-66, 2011
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