Rokitansky-Aschoff sinuses of the gallbladder are associated with black pigment gallstone formation: A scanning electron microscopy study

Rokitansky-Aschoff sinuses are the result of hyperplasia and herniation of epithelial cells through the fibromuscular layer of the gallbladder wall and are usually referred to as adenomyomatosis. The role of this study is to demonstrate that Rokitansky-Aschoff sinuses of the gallbladder are a risk factor for the formation of black pigment gallstones. A total of 179 removed gallbladders, were hystologically examinated. Sixty-four of the 179 consecutive cholecystomized patients had typical adenomyomatosis. Thirty-eight of the 64 patients with adenomyomatosis had black pigment gallstones, alone (n = 22) or in association with single (n = 12) or multiple (n = 4) cholesterol gallstones in the same gallbladder. Twelve of these patients did not have the typical risk factors for black stones (hemolysis, cirrhoses, gastrectomy, etc). Gallstones were examined by infrared spectroscopy and X-ray diffractometry. In addition, in a subset of 14 patients, the gallstones and the gallbladder wall were examined by scanning electron microscopy. At least in the initial phases of formation, Rokitansky-Aschoff sinuses were found close to small intraparietal vessels and sometimes they contained black pigment microstones. After the fourth to fifth decades of life, black gallstones can be found in the Rokitansky-Aschoff sinuses and in the main gallbladder lumen. Black pigment gallstones can form in Rokitansky-Aschoff sinuses of the gallbladder in absence of the typical risk factors for bilirubin suprasaturation of bile.