Acalculous variant of Mirizzi syndrome: Imaging and clinical characteristics

Mirizzi Syndrome is a rare disease that causes biliary obstruction in the setting of an impacted stone in the gallbladder neck or Hartmann's Pouch which exerts mass effect on the common duct; however, we have noticed inflammatory biliary narrowing in the absence of an offending gallstone in the setting of acute cholecystitis. The purpose of this study is to report the clinical and MRCP findings in a series of 10 patients with this variant of Mirizzi Syndrome.

A search of our institution's PACS and electronic medical record identified 10 patients with a diagnosis of acute cholecystitis and narrowing of the common duct on imaging in the absence of an impacted gallstone. Imaging and clinical findings were confirmed by two board-certified abdominal radiologists.

All patients presented with abdominal pain and an average elevated total bilirubin of 3.0 mg/dL. Seven patients had MRCP findings of complete narrowing of the CBD. Nine patients had intrahepatic biliary ductal dilation. All nine patients with gadoliniumenhanced MRCP displayed biliary wall thickening with enhancement adjacent to the gallbladder. Nine patients underwent cholecystectomy, one patient underwent percutaneous cholecystostomy. Average bilirubin upon discharge was within normal limits at 0.9 mg/dL after intervention. Two patients had follow-up MRCP showing resolution of biliary narrowing.

A variant of Mirizzi Syndrome occurs in the absence of an offending gallstone in the gallbladder neck or cystic duct to explain the biliary narrowing. We postulate that acute cholecystitis can cause a local inflammatory narrowing resulting in biliary obstruction.