Black pigment gallstones with cholesterol gallstones in the same gallbladder

We studied 1312 consecutive patients who underwent surgery for gallstones in the biliary tract at one university hospital in Siena, Italy, with a systematic classification of gallstones found within the gallbladder. Of these patients, 1226 were found to have gallbladder stones; 94 of these had black pigment gallstones. Of these, 13 patients were found to have black pigment gallstones and cholesterol gallstones within their gallbladder. They all had multiple black pigment gallstones, usually very small (all <6 mm diameter), in association with larger cholesterol stones in the gallbladder lumen. The cholesterol gallstones were single in seven cases, double in two cases, and multiple in four cases. All 13 of these patients with black pigment stones in association with cholesterol stones had histologic evidence of either adenomyomatosis or Rokitansky-Aschoff sinuses in the gallbladder wall. In nine of the 13 patients, the black pigment stones were located both in the gallbladder lumen and in close association with the gallbladder wall (in areas of adenomyomatosis or in Rokitanski-Aschoff sinuses). In the other four patients, the stones were found in close association with the gallbladder wall alone and not freely mobile within the gallbladder lumen. It is concluded that cholesterol stones and black pigment stones may be found in the same gallbladder. This association is infrequent with an incidence of 13 of 1226 (1.06%) in our series. There appears to be some relationship between the formation of the black pigment stones and the presence of adenomyomatosis or Rokitanski-Aschoff sinuses. However, the pathogenesis of these two compositionally distinctly different types of stones within the same gallbladder is not understood and deserves further study.