Black and Brown Pigment Gallstones Differ in Microstructure and Microcomposition

Abstract

The two subtypes of pigment gallstones, black and brown stones, differ in chemical composition and pathogenesis. We examined a black bilirubinate stone and a black phosphate stone (which represented opposite ends of the compositional spectrum of black noncarbonate stones), a black carbonate stone, and a brown pigment stone using scanning electron microscopy and microchemical techniques to determine if stone microstructure and microcomposition reflected different patterns of formation. The cross-sectional surfaces of the black bilirubinate and black phosphate stones were smooth and homogenous. Electron probe microanalysis demonstrated high concentrations of sulfur and copper in the center of the black bilirubinate stone; sulfur was in a low valence state consistent with disulfide linkages in proteins. The brown stone was rough-surfaced with lamellated bands on cross-section. The lighter-colored bands in this stone contained virtually all of the detected calcium palmitate, while the darker sections contained much more calcium bilirubinate. Plasma oxygen etching demonstrated a network of protein interdigitating with calcium bilirubinate salts in the black bilirubinate and black phosphate stones but not in the black carbonate or brown stones. Argon ion etching demonstrated that calcium bilirubinate was in a closely packed rod-shaped arrangement in all three black stones but not in the brown stone. We conclude that the marked differences in structure and composition between the black noncarbonate and brown pigment gallstones support the hypothesis that the two major pigment gallstone types form by different mechanisms. In addition, the layered structures of the black carbonate and brown stones suggest that stone growth is affected by cyclic changes in biliary composition.

Gallstone Classification in Western Countries

“…The ultrastructural analysis with scanning electron microscopy has proved to be useful in the classification and study of pigment gallstones [9,10,[16][17][18][19]. Moreover, the classification of gallstones based on thin-section petrographic microscopy does not consider brown pigment gallstones and should be enriched by the ultrastructural analysis of gallstones [18,19].…”

“…Moreover, the classification of gallstones based on thin-section petrographic microscopy does not consider brown pigment gallstones and should be enriched by the ultrastructural analysis of gallstones [18,19]. In addition, x-ray diffractometry analysis, as well as infrared spectroscopy of gallstones, is of fundamental importance for an accurate stone analysis [9,10,14,16,17]. An accurate study of gallstones is very useful to understand gallstone pathogenesis.…”

“…Gallstone prevalence in adult population ranges from 10 to 15 % [5]. Gallstones in Western countries are distinguished into the following classes: cholesterol gallstones that contain more than 50 % of cholesterol (nearly 75-80 % of gallstones) and pigment gallstones that contain less than 30 % of cholesterol by weight, which can be subdivided into black pigment gallstones (10-15 %) and brown pigment gallstones (5-10 %) [6][7][8][9][10][11] (Fig. 1).…”

“…1) are associated with typical hyperbilirubinbilia factors such as hemolysis, ineffective erythropoiesis, pathologic enterohepatic cycling of unconjugated bilirubin, and liver cirrhosis and with parietal gallbladder mucosa factors such as Rokitansky-Aschoff sinuses of the gallbladder [12,13]. Brown pigment gallstones are nearly 5 % of gallstones and are found mainly in the common bile duct; they are associated with biliary infection [8][9][10].…”

Characterisation of Gallstones Using Fourier Transform Infrared Spectroscopy

“…Brown, black stones are chemically, morphologically and clinically distinct. Black stones are formed in the gallbladder and are associated with hemolysis, cirrhosis and old age [5,6]. Classification of pigment stones was made on the basis of the proceeding of the first National Institute of Health-International Workshop on pigment gallstone diseases [7].…”