What layers should be excised in surgical deroofing of a hydatid liver cyst?

Surgical Deroofing of Hydatid Liver Cyst: Layers to Excise

In surgical deroofing of a hydatid liver cyst, the germinal and laminated layers should be excised, while preserving the adventitia (pericyst) layer (option D).

Understanding Hydatid Cyst Structure

Hydatid cysts consist of three distinct layers:

1. Germinal layer - The innermost layer containing the living parasite tissue
2. Laminated layer - The middle acellular layer
3. Pericyst/Adventitia - The outermost layer formed by compressed host liver tissue 1

Surgical Management Principles

The surgical approach to hydatid liver cysts should follow these principles:

Correct Layers for Excision

• The germinal and laminated layers must be completely removed as they contain the parasitic elements 2
• The pericyst (adventitia) should generally be preserved as it is composed of host tissue and forms a natural boundary 1

Surgical Technique for Deroofing

When performing surgical deroofing:

1. Surround the operative field with gauze soaked in scolicidal agent (e.g., hypertonic saline 20-21%)
2. Puncture and aspirate cyst contents
3. Inject scolicidal solution into the cyst cavity
4. Remove the germinal and laminated layers completely
5. Examine for biliary communications
6. Consider omentoplasty to fill the residual cavity 3, 4

Rationale for Layer Selection

• Complete removal of parasitic elements: The germinal layer contains the living parasite and must be completely removed to prevent recurrence 2
• Laminated layer removal: This acellular layer must also be removed as it can harbor daughter cysts and scolices 2, 5
• Preservation of pericyst: The pericyst is host tissue that forms a natural boundary between the parasite and liver parenchyma. Preserving it reduces the risk of bleeding and biliary leakage 1, 4

Important Considerations

• Pre-operative medical therapy with albendazole (10 mg/kg/day for 15 days) is recommended before surgical intervention 5
• Biliary fistula is the most common complication of hydatid cyst surgery (reported in up to 38.6% of cases) 4
• Intraoperative scolicidal agents are essential to prevent dissemination 3
• Laparoscopic approaches are increasingly being used with similar principles of layer removal 3

Alternative Approaches

While deroofing with removal of germinal and laminated layers is standard, other approaches may be considered in specific situations:

• Total pericystectomy: In select cases (7% in one series), complete removal of all layers including the pericyst may be performed 5
• PAIR technique (Puncture, Aspiration, Injection, Reaspiration): For uncomplicated cysts, this less invasive approach may be appropriate, but should only be performed in specialized centers 2, 6

The choice of surgical approach should be guided by cyst location, size, and presence of complications, but regardless of technique, the germinal and laminated layers must be completely removed while generally preserving the pericyst.