Diagnostic Ultrasound - Abdomen and Pelvis

Hepatic Cyst
TERMINOLOGY
Synonyms
• Hepatic or bile duct cyst; liver cyst
Definitions
• Benign, congenital or developmental, fluid-filled lesion with
cyst wall derived from biliary endothelium
IMAGING
General Features
• Best diagnostic clue
○ Anechoic lesion with posterior acoustic enhancement,
well-defined back wall, and no internal vascularity
• Location
○ Occur throughout liver
• Size
○ Varies from few mm to 10 cm
• Morphology
○ May be unilocular or multilocular with barely perceptible
septations
○ Anechoic fluid
○ Occasionally complicated by hemorrhage
• Key concepts
○ Current theory:True hepatic cysts arise from
hamartomatous tissue
○ Common benign liver lesion in 2-7% of population
○ Congenital or developmental: Simple hepatic or bile duct
cyst
– Solitary or multiple
– No communication with bile ducts
– More prevalent in women
– Usually asymptomatic
○ When > 10 in number, consider fibropolycystic diseases:
Autosomal dominant polycystic liver disease (ADPLD) (>
20 cysts is diagnostic for ADPLD), autosomal dominant
polycystic kidney disease (ADPKD), or biliary hamartomas
○ Acquired cyst-like hepatic lesions
– Trauma (seroma or biloma)
– Infection: Pyogenic or parasitic
– Neoplasm: Primary or metastatic
Ultrasonographic Findings
• Grayscale ultrasound
○ Uncomplicated simple (bile duct) cyst
– Anechoic rounded
– Well-defined back wall
– Posterior acoustic enhancement
– Smooth or lobulated borders
– Thin or nondetectable wall
– No or few barely perceptible septations
– No mural nodules or wall calcification
– Do not cross segments
– Normal adjacent liver parenchyma
○ Hemorrhagic or infected hepatic cyst
– Internal debris (clots or fibrin strands) may layer or be
dispersed within cyst
– Septation/thickened wall
– ± calcification
○ Autosomal dominant polycystic liver disease
– Multiple cysts (> 10) 1-10 cm in size
– Anechoic or with debris due to hemorrhage or
infection
– Calcification of some cyst walls
– May have barely perceptible septations but no mural
nodularity
– Liver often distorted by innumerable cysts
– In severe cases, little hepatic parenchyma is preserved;
segmental liver anatomy and normal shape disappear
– Look at kidneys for presence of cysts (ADPKD)
• Color Doppler
○ Adjacent vessels may be distorted by large cysts
○ No internal or mural vascularity
CT Findings
• NECT
○ Simple liver or bile duct cyst
– Well-defined margins with smooth, thin walls
– Water density (-10 to +10 HU)
– No septations or barely perceptible septations,
typically up to 2 thin septa
– No fluid-debris levels, mural nodularity, or wall
calcification
○ When complicated by hemorrhage, layering debris may
be hyperdense or lesion may mimic tumor
• CECT
○ Simple hepatic cyst or ADPLD
– Uncomplicated or complicated (infected): No
enhancement
MR Findings
• Simple hepatic cyst or ADPLD
○ T1WI: Hypointense
○ T2WI: Hyperintense
– Markedly increased signal intensity due to pure fluid
content
– Sometimes indistinguishable from a typical
hemangioma
○ MRCP: No communication with bile duct
• Complicated (hemorrhagic) cyst
○ T1WI & T2WI
– Varied signal intensity (due to mixed blood products)
– ± fluid level
• T1WI C+: No enhancement
Imaging Recommendations
• Best imaging tool
○ Ultrasonography
○ In some indeterminate lesions seen on CT or MR,
ultrasound may help characterize lesions as cystic
DIFFERENTIAL DIAGNOSIS
Cystic or Necrotic Metastases
• No posterior acoustic enhancement
• Debris, mural nodularity, or thick septa
• Wall vascularity
Pyogenic Abscess
• Complex cystic mass with debris
• Thick or thin multiple septations
• Mural nodularity & vascularity
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Diagnoses: Liver
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