A 60-year-old diabetic man is admitted to the hospital with a diagnosis of acute cholecystitis. The WBC count is 28,000, and a plain film of the abdomen and CT scan show evidence of intramural gas in the gallbladder. What is the most likely diagnosis?

Emphysematous cholecystitis is caused by gas-forming organisms. On a plain x-ray of the abdomen, gas may be seen within the wall of the gallbladder. Clinically, the patient has rapidly progressive sepsis, RUQ pain, fever, and hemodynamic instability. The disease primarily affects diabetic men. Treatment with laparotomy and cholecystectomy is urgent to avoid complications. Air within the biliary tree (not gallbladder wall) may be seen in gallstone ileus, after biliary- enteric anastomosis or after sphincterotomy.