Brown type gallstones are formed due to:: (A) Hypercholesterolemia, (B) Long standing hemolysis, (C) Chronic biliary infection, (D) Drugs
Answer is C. Pigment stones are composed of calcium bilirubinate and are classified into "black" and "brown" types, the latter forming secondary to chronic biliary infection. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Pages 2616-17