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Pictorial Essay

Abdominal imaging

SUBMISSION: 29/03/2023 - ACCEPTANCE: 01/06/2023

Von Meyenburg Complexes

(biliary hamartomas): Imaging with US ,

CT and MRI.

Ekaterini Manavi

, Despoina Seredou

, Soa Gioulvanidou

, Sotiria Zonitsa

Athanasios Papaefthymiou-Papakonstantinou

, Ioannis Tsitouridis

Radiology Department “Agios Dimitrios” General Hospital, Thessaloniki, Greece.

Radiology Department General Hospital, Veria , Greece.

Abstract

Purpose. The purpose of this study is to describe the

radiological characteristics of Von Meyenburg com-

plexes, a generally benign condition that may be con-

fused with other entities and to emphasize on its rela-

tionship with other diseases.

Methods. We studied 21 patients over a period of 10

years aged between 21 and 54 years old which were

evaluated with Ultrasound(US) and/or Computed To-

mography(CT),Magnetic Resonance Imaging(MRI) mo-

dalities.

Results. In 16 of our patients Von Meyenburg Complex-

es were found exclusively, in 3 patients in combination

with simple cysts, in one patient in combination with

peribiliary cysts and in the last one in combination with

peribiliary cysts and ADPKD (autosomal dominant poly-

cystic kidney disease).

Conclusions. The knowledge of the pathology and radi-

ological appearance of Von Meyenburg complexes con-

tributes to the establishment of correct diagnosis and

the avoidance of unnecessary interventions.

Corresponding

Author,

Guarantor

E-mail: Ioannis Tsitouridis, Radiology Department, Agios Dimitrios General Hospital,

Thessaloniki, Greece, Email: tsitouridis1@gmail.com

Key words

Von Meyenburg Complex, biliary hamartomas , Imaging,MRI, CT , US

Von Meyenburg Complexes(biliary hamartomas): Imaging with US , CT and MRI, p. 36-43

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Introduction

Von Meyenburg complexes (VMCs) or multiple bil-

iary hamartomas are small (<10 mm) benign liver le-

sions which represent cystic dilated bile ducts, lined by

a single layer of cuboid epithelium and surrounded by

abundant brous stroma,which sometimes is hyalin-

ized [1].

The lumen of the dilated bile ducts of VMCs may con-

tain clear bile, inspissated bile, polypoid projections ,in

the lumen or islands of connective tissue.

Their pathogenesis is attributed to ductal plate mal-

formations involving the smaller interlobular bile ducts

in the late phase of embryologic development of the

intrahepatic bile ducts(a factor arresting or perturb-

ing the remodeling of the ductal plates) [2, 3].The large

number of bile ducts proles and the continuity with

the portal tracts suggest a pollard willow abnormality

in the branching pattern of the peripheral portal vein

ramications [2].

Their prevalence is around 5,6% in autopsy series[4].

The biliary hamartomas are well- circumscribed, irreg-

ular or round structures which can be found into the

liver, especially in the subcapsular area,in continuity

with or merged into the portal tracts [5,6]. They may

contain sclerotic arteries or be devoid of vessels [5].

We estimated 21 patients with VMCs with US, CT and

MRI.

CT scans were obtained by a SIEMENS Somatom Per-

spective 16 machine with a 2mm scan width before and

after intravenous contrast material administration.

MRI images were obtained using a 1,5 Tesla PHILLIPS

machine.

From these 21 patients16 revealed only VMCs, 1

patient had also peribiliary cysts, 3 patients had also

simple liver cysts and the last patient had simple cysts,

peribiliary cysts and ADPKD (autosomal dominant pol-

ycystic kidney disease) (g.1). 3 patients had a biop-

sy and histological results conrmed the diagnosis of

VMCs.

Ultrasound examination of the liver was negative in

11 cases and in the rest of the cases it was very dif-

cult to identify the accurate number of the lesions. In

3 cases the

VMCs appeared as echogenic small dots with

and without the comet-tail artifact (g.3). In 3 pa-

tientsVMCs reveal a cystic appearance with posterior

enhancement (g.4) (g.6) .

CT exams of the liver were able only in 6 cases to de-

tect the lesions with low sensitivity (g.8).

MRI exams especially with T2-weighted sequences

and MR Cholangiography were better both in the visu-

alization and in the conrmation of the exact number

of lesions (g.2).

Discussion

Von Meyenburg Complexes (VMCs) are ductal plate,

non cancerous malformations of the liver that are usu-

ally diagnosed on imaging studies. There has been de-

scribed association of VMCs with autosomal dominant

polycystic kidney disease (ADPKD), simple liver cysts,

peribiliary cysts and pancreatic cysts [2,4,7].

The malignant transformation of biliary hamartomas

to intrahepatic Cholangiocarcinoma is rare [8,9,10].

This has been found to occur due to gradual transition

from VMCs to hyperplastic or adenomatous lesions and

then progress to malignant transformation [11].

There is heterogeneity in ultrasound imaging nd-

ings that actually reects the histological features, in-

cluding the amount of uid or inspissated bile of the

dilated ducts and the brous stroma surrounding them

[12]. The multiple biliary hamartomas may appear as

micro-nodules , hypo- or hyperechoic depending from

the material inside the lumen of the dilated bile ducts

[13,14,15]. There has been described a typical imaging

nding of multiple comet-tail echoes [16], representing

the posterior enhancement of the tiny cystic lesions.

Furthermore, some of the hyperechoic lesions are

found to be cystic when magnication is applied[13].

On plain CT , VMCs appear as multiple round or ir-

regular hypoattenuating lesions in both hepatic lobes

[12,13,17]. In most of the cases there is no enhance-

ment of the lesions after intravenous administration

of contrast medium (poor vascularity) , but the biliary

hamartomas become more clearly visible [13].However

homogeneous enhancement has been reported, possi-

bly concerning lesions with prevalent brous stroma

[18,19].

VMCs are well-circumscribed round or irregular le-

sions which tend to be hypointense on T1-weighted im-

ages and show markedly high intensity on T2-weighted

images, due to the uid- containing ductules [13, 19,

20,21,22].In some cases the high T2 signal is attenuat-

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Figure 1

(a,b,c) axial post-contrast (cholangi-

ographic contrast media) CT images

which reveal the peribiliary cysts,

simple cysts and cysts in the kidneys

(ADPKD)

Figure 2

(a,b,c,d) axial T2WI and MR Cholangiography which

clearly depicts the VMCs, peribiliary cysts, simple

cysts and the cysts in the kidneys (ADPKD).

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ed by the low signal intensity of the brous tissue [20].

Where the echo time increase at T2- sequences , the sig-

nal intensity increases and becomes similar to cerebro-

spinal uid[19,21,22]. On diffusion- weighted sequences

, biliary hamartomas mimic cystic lesions ,as they have

a high apparent diffusion coefcient [23].

MR Cholangiography has been considered to be high-

ly sensitive in demonstrating both the biliary tree and

the cystic liver lesions, including their relationship with

the ducts [24,25]. Additionally, MRCholangiography dis-

plays more lesions and delineates better their shape

than conventional MRI , because of its higher contrast

resolution [13,24 ] (g.7).There are no abnormalities af-

fecting the biliary system and there is no obvious com-

munication of the VMCs with the biliary system [13, 22].

Sometimes ,on T2-weighted images and MR Cholangi-

ography the image of multiple VMCs have the appear-

ance of a <<starry sky>> [26[ (g.5).

On T1- weighted images after administration of gad-

olinium there has been described different patterns

ranging from no enhancement [12, 13 ] to homogeneous

enhancement [19].A thin regular rim of early dynamic

enhancement on early dynamic images that persists on

late images may be observed and represents compressed

liver parenchyma and inammatory cells surrounding

the hamartomas[24, 27]. Finally, a small enhancing mu-

ral nodule has been described ,which correlates histo-

pathologically with an endocystic polypoid projection

of collageneous supporting tissue, and is considered

specic for VMCs [22]. The nodule appears isointense to

liver parenchyma on T1- weighted images ,of interme-

diate signal on T2-weighted images and shows enhance-

ment in all phases , including the delayed ones . The ad-

ministration of contrast material with biliary excretion

does not aggregate in hamartomas [23] (g.9) (g.10).

The VMCs must primarily be distinguished from

small metastases, especially in patients with a known

malignancy. Τhe lesions found in patients with biliary

hamartomas are relatively uniform and less than 1 cm

in size . In addition, they show varying degrees of en-

hancement after intravenous administration of contrast

medium. Even when the VMCs show a peripheral rim of

enhancement, it is thin and regular, as opposed to liver

metastases, in which thicker, irregular and progressive

Figure 3

(a,b,) Oblique sagittal sonograms of the liver which reveal VMCs as

echogenic dots with the comet-tail artifact.

(c,d) axial post contrast CT images which are negative for VMCs in

the liver.

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Figure 4

(a,b,c) oblique transverse sonograms which reveal many VMCs as echogenic dots with posterior comet-tail artifact.

Figure 5

(a,b,c) axial T2WI ,( d,e f) post-contrast T1WI and (g) MR Cholangiography, which

reveal multiple VMCs in the liver like a starry sky.

Figure 6

(a,b) oblique transverse sonograms which

reveal some VMCs with cystic appearance.

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Figure 7

(a,b) axial T2WI, (c,d) axial post-con-

trast T1WI and ( e) MR Cholangiog-

raphy which reveal clearly the VMCs

as cysts.

Figure 8

(a,b,c) axial post contrast CT scans

which reveal no liver abnormality .

(d,e) axial T2WI which reveal

multiple biliary hamartomas in the

periphery of the right lobe.

centripetal enhancement is observed. On T2-weight-

ed images, the biliary hamartomas show hyperintense

signal , which helps differentiate them from metasta-

ses. The latter are not visible when small on MR Chol-

angiography, unlike VMCs.Also unlike metastasis on

T2-weighted images with a longer echo time, VMCs re-

veal an increased signal intensity.

In conclusion, diffusion-weighted MRI may be useful,

as biliary hamartomas have a high apparent diffusion

coefcient.

The differential diagnosis also includes multiple mi-

croabscesses, but the clinical context is important. Pa-

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tients are almost always critically ill or even immu-

nosuppresssed with a swinging fever and right upper

quadrant abdominal tenderness. The abscesses show

diffusion restriction on MRI and “target” appearance

on US. Other conditions from which VMCs must be dif-

ferentiated are: multiple hepatic cysts (there are le-

sions that are larger than 1 cm, round in shape,do not

enhance and sometimes coexist with polycystic kidney

disease), peribiliary cysts (they are located exclusively

in the hepatic hilum and along the larger bile ducts),

dilated bile ducts, diffuse primary hepatocellular car-

cinoma (usually in cirrhotic patients), Caroli’s disease

(the “cysts” communicate with the biliary tree at MR-

Cholangiography and demonstrate enhancing “central

dot sign” , which corresponds to the intraluminal por-

tal vein branch).

In our study we found out that the T2-weighted se-

quences and MR Chongiography were the most valua-

ble in the imaging of the VMCs.

Conclusion

VMCs are benign liver malformations and their cor-

rect diagnosis can be made when the typical imaging

ndings are present without histological conrmation,

thanks to the higher resolution and the advance of the

imaging techniques. R

Funding

The project did not receive any specic funding.

Conict of interest

The authors declared no conicts of interest.

Figure 9

(a,b) axial T2WI which reveal many VMCs

Figure 10

(a,b) axial post contrast T1WI. VMCs have a cystic appearance without enhancement after contrast medium administration.

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Ready - Made

Citation

Manavi E, Seredou D, Gioulvanidou S, Zonitsa S, Papaefthymiou-Papakon-

stantinou A, Tsitouridis I. Von Meyenburg Complexes(biliary hamartomas):

Imaging with US , CT and MRI. Hell J Radiol 2023; 8(3): 36-43.

Von Meyenburg Complexes(biliary hamartomas): Imaging with US , CT and MRI, p. 36-43