Hepatic Cyst

Published on 20/07/2015 by admin

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Last modified 20/07/2015

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 Simple hepatic or bile duct cyst

• Often multiple: Usually < 10

image When > 10, consider autosomal dominant polycystic liver disease (ADPLD) or biliary hamartomas
• Sharply defined margins, thin walls
• Water density (-10 to +10 HU)
• Usually no or few thin septations

image No mural nodularity or wall calcification
• Hemorrhage into cyst may simulate tumor

image No enhancement of “solid” material
image Varied MR signal intensity (due to mixed blood products)
• US: Anechoic mass, accentuated through transmission

image Smooth borders; thin or invisible wall
• Size varies from few mm to > 20 cm

image Rarely are the cysts of similar size
image Helps to differentiate from biliary hamartomas, which are all usually < 15 mm

TOP DIFFERENTIAL DIAGNOSES

• AD polycystic disease, liver
• Cystic or necrotic metastases
• Biliary cystadenocarcinoma
• Biliary hamartomas
• Ciliated hepatic foregut cyst
• Hepatic cavernous hemangioma
• Biloma
• Hepatic pyogenic abscess
• Hydatid (echinococcal) disease

DIAGNOSTIC CHECKLIST

• Sonography shows cyst morphology better than CT
image
(Left) Axial CECT shows a spherical hepatic mass image with water density and homogeneous contents. No internal debris or wall irregularities are present. This is a classic simple cyst.

image
(Right) Ultrasound in the same patient shows an anechoic mass image with accentuated through-transmission image. Either CT or US would have been sufficient to establish the diagnosis in this patient.
image
(Left) Axial T1WI MR shows a large, cystic, hepatic mass image that has homogeneous low intensity and several thin septa image.

image
(Right) Coronal T2WI shows uniform high intensity and septa image. The cyst has remained stable for years, and no other evaluation or intervention was performed.

TERMINOLOGY

Synonyms

• Simple hepatic or bile duct cyst

Definitions

• Benign, congenital, developmental lesion derived from biliary endothelium

IMAGING

General Features

• Best diagnostic clue

image Anechoic lesion with increased through-transmission and no mural nodularity on US
• Location

image Any location within liver
• Size

image Varies from few mm to > 20 cm

– Rarely are the cysts of similar size
– Helps to differentiate from biliary hamartomas, which are all usually < 15 mm
• Morphology

image Spherical or oval, well marginated
• Key concepts

image Classified based on etiology and pathogenesis
image Congenital or developmental: Simple hepatic or bile duct cyst

– Often multiple: Usually < 10
– No communication with bile ducts
image When > 10 in number, fibropolycystic disease must be considered

– i.e., autosomal dominant polycystic liver disease (ADPLD) or biliary hamartomas

CT Findings

• NECT

image Simple liver or bile duct cyst

– Sharply defined margins; thin walls
– Water density (-10 to +10 HU)
– Usually no septations (uncommonly ≥ 1 thin septa)
– No fluid-debris levels
– No mural nodularity or wall calcification
image Hemorrhage into cyst may be indistinguishable from tumor

– Mural nodularity, fluid-debris level
– No enhancement of “solid” material
• CECT

image Simple cyst

– Uncomplicated or complex

image No enhancement of cyst contents

MR Findings

• Simple hepatic cyst

image T1WI: Hypointense
image Heavily T2WI

– Markedly increased signal intensity due to pure fluid content
– Sometimes indistinguishable from hemangioma
• Complicated (hemorrhagic) cyst

image T1WI and T2WI

– Higher signal intensity (due to mixed blood products)
– may or may not show fluid level
• T1 C+

image Uncomplicated or complicated cyst

– No enhancement of contents
• MRCP

image Shows no communication with bile ducts

Ultrasonographic Findings

• Grayscale ultrasound

image Uncomplicated simple cyst

– Anechoic mass; accentuated through transmission
– Smooth borders; thin or invisible wall
– No or few septations
– No mural nodules or wall calcification
image Hemorrhagic or infected hepatic cyst

– Septations, internal debris
– Thickened wall
– ± calcification

Nonvascular Interventions

• Cyst aspiration may be helpful in confirming infected or hemorrhagic cyst

Imaging Recommendations

• Best imaging tool

image Ultrasound, CT, or MR
• Protocol advice

image CT or MR should include unenhanced and contrast-enhanced series
image Obtain thin axial CT sections to minimize partial volume averaging and to facilitate multiplanar reformations

DIFFERENTIAL DIAGNOSIS

AD Polycystic Disease, Liver

• Hepatic cysts are multiple, of varying sizes, enlarge and distort liver
• Often have contents of complex fluid due to prior hemorrhage
• Cysts in other organs (50% have renal polycystic disease) ± family history of polycystic disease

Cystic or Necrotic Metastases

• Most common with sarcoma metastases and gastrointestinal stromal tumor (GIST)

image Especially likely to resemble cysts after chemotherapy
• Enhancing mural nodules, thick septa
• 

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