Which of the following statements about pigment gallstones is correct?

• A They form from supersaturation of bile with cholesterol due to excess biliary cholesterol secretion
• B Brown pigment stones form primarily inside the gallbladder in sterile bile
• C Black pigment stones contain calcium bilirubinate and are associated with extravascular haemolysis ✓
• D Black pigment stones occur predominantly in East Asian populations

Explanation

Black pigment stones are composed of calcium bilirubinate and polymerized bilirubin; they form in the gallbladder when unconjugated bilirubin rises, classically in chronic extravascular haemolysis such as hereditary spherocytosis or sickle cell disease. Brown pigment stones form in infected bile ducts through bacterial beta-glucuronidase and are more common in East Asia, making D wrong. Option A describes cholesterol stone formation.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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