Black pigment stone in a male child aged two years and seven months

Black pigment or polybilirubinate gallstones: composition and formation

Black pigment, extracted from gallstones from patients, has been characterized as polybilirubinate. A similar material with the same physical properties was synthesized from bilirubin. The properties of black pigment are described. A mechanism for black pigment formation is postulated, and the possible relationship of this pigment to the formation of gallstones is discussed.