What is Mirizzi syndrome and its types?

Mirizzi Syndrome and Its Classification

Mirizzi syndrome is a rare complication of gallstone disease characterized by extrinsic compression of the common hepatic duct due to an impacted stone in the cystic duct or gallbladder neck, occurring in less than 1% of patients with gallstones. 1

Definition and Pathophysiology

Mirizzi syndrome occurs when a gallstone becomes impacted in either:

• The cystic duct
• The neck of the gallbladder (Hartmann's pouch)

This impaction leads to:

• Extrinsic compression of the common hepatic duct
• Inflammatory response in the surrounding tissues
• Potential development of cholecystobiliary fistula in advanced cases 2

Classification

The classification of Mirizzi syndrome has evolved over time, with the most widely accepted being the Csendes classification system that divides it into four types based on the extent of bile duct involvement 3:

1. Type I: External compression of the common hepatic duct by a stone impacted in the cystic duct or gallbladder neck without fistula formation

2. Type II: Presence of a cholecystobiliary fistula involving less than one-third of the circumference of the common bile duct

3. Type III: Cholecystobiliary fistula involving up to two-thirds of the bile duct circumference

4. Type IV: Complete destruction of the bile duct wall with cholecystobiliary fistula involving the entire circumference

Some classifications include a Type V, which involves a cholecystoenteric fistula (typically cholecystoduodenal) in addition to a cholecystobiliary fistula 3.

Clinical Presentation

Patients with Mirizzi syndrome typically present with:

• Obstructive jaundice (prominent in all patients in case series) 4
• Right upper quadrant pain
• Fever and chills (in cases with associated cholangitis)
• Elevated liver enzymes with a cholestatic pattern

Diagnostic Evaluation

Accurate diagnosis is critical as Mirizzi syndrome can mimic cholangiocarcinoma and other perihilar biliary strictures 1. The diagnostic approach includes:

1. Imaging studies:

   • Biliary MRI and multiphase liver CT should be performed first 1
   • Ultrasound typically shows a large stone in the gallbladder neck 4

2. ERCP (gold standard):

   • Demonstrates filling defect in the biliary tract at the cystic duct level
   • Can identify cholecystobiliary fistula if present
   • Allows for brush cytology and forceps biopsy (minimum five passes for brush cytology and three samples for forceps biopsy) 1

3. Key diagnostic findings:

   • Large stone in gallbladder neck
   • Extrinsic compression of common hepatic duct
   • Filling defect at cystic duct level on cholangiogram
   • Excavated filling defect or block of common duct (suggests fistula) 4

Management

Treatment depends on the type of Mirizzi syndrome:

1. Type I:

   • Simple cholecystectomy may be sufficient 4
   • Laparoscopic approach may be considered in carefully selected patients at specialized centers 1

2. Types II-IV:

   • Open surgery is the standard approach due to complex anatomy and high risk of bile duct injury 1
   • Partial cholecystectomy with choledochoplasty using a gallbladder flap and T-tube insertion is often required 4
   • For extensive defects, biliodigestive anastomosis may be necessary

Important Considerations

1. Mirizzi syndrome is a contraindication for routine laparoscopic cholecystectomy due to high risk of common bile duct injury 4

2. Preoperative diagnosis significantly facilitates surgical management and reduces complications 5

3. Potential complications include:

   • Bile duct injury during surgery
   • Postoperative bile leak
   • Stricture formation
   • Recurrent cholangitis 1

4. Endoscopic treatment may be considered as a temporizing measure or for high-risk patients 1

Mirizzi syndrome remains a challenging condition that requires careful preoperative planning and experienced surgical management to avoid the significant morbidity associated with bile duct injuries.