What is the workup for liver cysts with septation?

Workup of Liver Cysts with Septation

MRI is the gold standard imaging modality for characterizing hepatic cysts with septation, as it provides superior assessment of worrisome features that may indicate mucinous cystic neoplasms (MCNs) requiring surgical resection. 1

Initial Assessment and Imaging

When a liver cyst with septation is identified, the primary goal is to differentiate between benign simple cysts and potentially malignant mucinous cystic neoplasms (MCNs). The workup should follow this algorithm:

1. Initial ultrasound evaluation:

   • Assesses basic cyst characteristics (size, location, number)
   • Identifies presence of septations
   • Evaluates for posterior enhancement and anechoic content typical of simple cysts
   • Limited in fully characterizing complex internal architecture 1

2. MRI with contrast (recommended for all cysts with septation):

   • Superior for detecting and characterizing septations
   • Evaluates signal intensity on T1 and T2-weighted sequences
   • Assesses for enhancement of septations or nodules
   • Can identify hemorrhagic or proteinaceous contents 1, 2

3. Laboratory testing:

   • Liver function tests
   • Tumor markers (CEA, CA 19-9) may be elevated in MCNs, particularly with invasive carcinoma, though diagnostic accuracy is limited 1

Key Features to Evaluate

The 2022 EASL guidelines 1 define specific worrisome features that help differentiate MCNs from simple cysts:

Major Worrisome Features:

• Thick septation
• Nodularity

Minor Worrisome Features:

• Upstream biliary dilatation
• Thin septations
• Internal hemorrhage
• Perfusional change
• <3 coexistent hepatic cysts

A combination of ≥1 major and ≥1 minor feature should raise suspicion for MCNs 1. The morphology of septations is particularly important - septations arising from the cyst wall without external indentation have a very high association with MCNs 1, 3.

Diagnostic Algorithm

1. For cysts with no worrisome features:

   • Routine follow-up imaging (usually ultrasound)
   • No intervention needed if asymptomatic

2. For cysts with worrisome features:

   • MRI is mandatory for complete characterization 1
   • Multidisciplinary team evaluation involving hepatogastroenterologists, radiologists, surgeons, and pathologists 1
   • Consider surgical consultation

3. When MCN is suspected:

   • Complete surgical resection is the gold standard treatment 1
   • Frozen section during surgery can guide extent of resection 4

Important Clinical Considerations

• MCNs occur predominantly in middle-aged women and are commonly symptomatic (86%) 1
• The combination of thick septations/nodularity plus at least one additional associated feature carries high specificity (94-98%) for MCNs 2
• MRI is more accurate than CT in detecting features that differentiate MCNs from simple cysts 2
• Fenestration alone is associated with higher rates of tumor recurrence in MCNs and should be avoided when MCN is suspected 1
• Complicated hepatic cysts (infection or hemorrhage) may mimic MCNs on imaging, making accurate diagnosis challenging 1

Common Pitfalls to Avoid

1. Relying solely on CT imaging: MRI is superior for characterizing cystic lesions and should be used when septations are present 1, 2

2. Misinterpreting hemorrhagic simple cysts as MCNs: Internal hemorrhage is more common in simple cysts and doesn't necessarily indicate malignancy 1

3. Inadequate follow-up of indeterminate cysts: Cysts with worrisome features require proper characterization and monitoring

4. Performing fenestration without frozen section: When surgical intervention is planned for cysts with worrisome features, frozen section should be considered to guide the extent of resection 4

5. Overlooking septation morphology: The relationship between septations and the cyst wall (septations arising without external indentation) is highly associated with MCNs 3

By following this evidence-based approach, clinicians can appropriately identify and manage liver cysts with septation, ensuring proper treatment for potentially malignant lesions while avoiding unnecessary interventions for benign cysts.