Brown Gallstone


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A pigment gallstone formed from a complex mixture of insoluble calcium salts of unconjugated bilirubin with varying amounts of protein and cholesterol. While black gallstones are found in sterile bile in the gallbladder, brown gallstones are often associated with infection (e.g., with Escherichia coli, Ascaris lumbricoides, Opisthorchis sinenesis). These organisms release beta-glucuronidases, which hydrolyze bilirubin glucuronides; in contrast to black stones