Cholesterol crystal embolisation as a cause of an intraluminal mass in the gallbladder mimicking carcinoma

An 82-year-old man had attended our hospital regularly for treatment of hypertension, angina pectoris and for follow up of abdominal aortic aneurysm. He had undergone pneumonectomy. A screening abdominal US found a protruding lesion on the inner wall of the gallbladder. Though the muscular layer of the gallbladder seemed intact on endoscopic US, we could not rule out malignancy. We performed whole layer cholecystectomy, and found a 25×15 mm black tumor in the body of the gallbladder. Pathologically, the protruding lesion consisted of necrosis and fibrin. Small arteries around the protruding lesion were occluded by multiple needle-shaped cholesterol clefts. According to the pathological study, we concluded the protruding lesion was granulation tissue developed due to ischemia and inflammation induced by cholesterol crystal embolization (CCE). We can find no cases of the protruding lesion in the gallbladder caused by CCE in PubMed, so it must be a very rare case.