Biliary Hamartoma

Published on 09/08/2015 by admin

Filed under Radiology

Last modified 09/08/2015

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 a.k.a. von Meyenburg complex

image Asymptomatic and of no clinical concern

IMAGING

• Multiple, near water density/intensity liver lesions < 15 mm in diameter

image Varied enhancement based on cystic and solid components
image No communication with biliary tree
• US: Small and well-circumscribed lesions

image Often have echogenic walls with small fluid content
• US shows much more echogenicity and fewer cystic lesions than anticipated based on prior CT or MR

TOP DIFFERENTIAL DIAGNOSES

• Autosomal dominant polycystic liver disease

image Larger, more numerous cysts in liver and other organs
• Multiple simple hepatic cysts

image Fewer cysts of varying size; no mural nodules
• Caroli disease

image Central dot sign on CECT and MR
image ERCP and MRCP: Communicating bile duct abnormality
• Multiple/solitary, small metastatic lesions

image More complex and varied in size
• Opportunistic infection (microabscesses)

image Must be considered in immunosuppressed patient with fever

DIAGNOSTIC CHECKLIST

• No further evaluation needed when seen as isolated finding in healthy, nononcologic patient
• Should be considered as likely diagnosis in setting of innumerable small, slightly complex “cysts” in healthy patient
• Lesions appear more echogenic than expected on sonography
image
(Left) Axial T2WI MR shows innumerable tiny bright foci throughout the liver image, representing biliary hamartomas. This patient also had evidence of congenital hepatic fibrosis on imaging and liver biopsy, both part of the congenital hepatic and renal fibropolycystic disease spectrum.

image
(Right) MRCP shows small spherical cyst-like lesions image that do not communicate with the (normal) biliary tree. This feature helps to distinguish biliary hamartomas from Caroli disease.
image
(Left) Sonographic image shows innumerable tiny echogenic foci image throughout the liver and 1 of ∼ 10 cyst-like lesions image, though even these have small foci of echogenicity within the wall. MR on this patient showed many more cystic-appearing biliary hamartomas.

image
(Right) The branching, angulated glands in biliary hamartomas are lined by a single layer of flattened cuboidal epithelium. These glands may expand or rupture to produce small “cysts.” There is no nuclear atypia. (Courtesy S. Kakar, MD.)

TERMINOLOGY

Synonyms

• Bile duct microhamartoma
• von Meyenburg complex

Definitions

• Uncommon benign malformations of biliary tract

IMAGING

General Features

• Best diagnostic clue

image Multiple near water density/intensity liver lesions < 15 mm in diameter
• Location

image Subcapsular or intraparenchymal in location
image Scattered throughout both lobes of liver
• Size
• Irregular spherical
• Usually multiple to innumerable

CT Findings

• NECT

image Density of lesions depends on predominance of cystic or solid component

– Predominantly cystic: Water density
– Predominantly solid (fibrous stroma): Soft tissue attenuation
• CECT

image Cystic components remain near water density

– No enhancement of contents
image Solid (fibrous stroma) components enhance

– Usually become nearly isodense to liver
image Punctate calcifications may be seen

MR Findings

• T1WI

image Hypointense (both cystic and solid lesions)
• T2WI

image Very hyperintense (cystic components)
image Intermediate intensity (solid lesions)
image Heavily T2WI: Remain hyperintense (equal to fluid)

– 
• T1WI C+

image No enhancement of cystic components

– ± nodular enhancement of fibrous nodules
• MR cholangiography (MRC)

image Markedly hyperintense lesions
image No communication with biliary tree

Ultrasonographic Findings

• Grayscale ultrasound

image Multiple small and well-circumscribed lesions
image Fibrotic parts of lesions are very echogenic

– Reflect solid and cystic components
– Fluid or cystic component is sonolucent

image ± posterior acoustic enhancement
– US shows much more echogenicity and fewer cystic lesions than anticipated based on prior CT or MR

Angiographic Findings

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