Brown Pigment Gallstones : Composition

Brown Pigment Gallstones - Composition: They are composed of calcium salts of unconjugated bilirubin (monomeric calcium bilirubinate) and calcium salts of fatty acids (palmitate, stearate) in a glycoprotein matrix. Brown pigments stones have a higher amount of cholesterol than black pigment stones. They may also have small quantities of bile salts, phospholipids, and bacterial residues. The cut surface has stratified (lamellated) appearance with calcium bilirubinate-rich layers alternating with calcium palmitate-rich layers.

Note the close resemblance of brown pigment gallstones to fecal matter in this photograph. Image courtesy of: Dr. Ibrahim Zardawi; used with permission.