Page 654 - Robbins Basic Pathology by Vinay Kumar, Abul K. Abbas, Jon C. Aster

640 C H A P T E R 15 Liver, Gallbladder, and Biliary Tract Figure 15–35 Cholesterol gallstones. Mechanical manipulation during
laparoscopic cholecystectomy has caused fragmentation of several cho-
Table 15–8 Risk Factors for Gallstones lesterol gallstones, revealing interiors that are pigmented because of
Cholesterol Stones entrapped bile pigments. The gallbladder mucosa is reddened and irregu-
Demography: Northern Europeans, North and South Americans, Native lar as a result of coexistent acute and chronic cholecystitis.

Americans, Mexican Americans they can occur singly, but most often there are several, with
Advancing age faceted surfaces resulting from their apposition. Most cho-
Female sex hormones lesterol stones are radiolucent, although as many as
20% may have sufficient calcium carbonate to be
Female gender radiopaque.
Oral contraceptives
Pregnancy Pigment stones may arise anywhere in the biliary tree
Obesity and insulin resistance and are classified into black and brown stones. In general,
Rapid weight reduction black pigment stones are found in sterile gallbladder bile,
Gallbladder stasis while brown stones are found in infected intrahepatic or
Inborn disorders of bile acid metabolism extrahepatic ducts. The stones contain calcium salts of
Dyslipidemia syndromes unconjugated bilirubin and lesser amounts of other calcium
Pigment Stones salts, mucin glycoproteins, and cholesterol. Black stones are
Demography: Asian more than Western, rural more than urban usually small in size, fragile to the touch, and numerous (Fig.
Chronic hemolysis (e.g., sickle cell anemia, hereditary spherocytosis) 15–36). Brown stones tend to be single or few in number
Biliary infection and to have a soft, greasy, soaplike consistency that results
Gastrointestinal disorders: ileal disease (e.g., Crohn disease), ileal from the presence of retained fatty acid salts released by the
resection or bypass, cystic fibrosis with pancreatic insufficiency action of bacterial phospholipases on biliary lecithins. Because
of calcium carbonates and phosphates, 50% to 75% of
hemolytic anemias and infections of the biliary tract. The black stones are radiopaque. Brown stones, which
precipitates are primarily insoluble calcium bilirubinate salts. contain calcium soaps, are radiolucent.

The major risk factors for gallstones are listed in Table
15–8. Up to 80% of people with gallstones, however, have
no identifiable risk factors other than age and gender. Some
elaboration on these risk factors follows:
• Age and gender. The prevalence of gallstones increases

throughout life. In the United States, less than 5% to 6%
of the population younger than age 40 has stones, in
contrast with 25% to 30% of those older than 80 years.
The prevalence in women of all ages is about twice as high
as in men.
• Ethnic and geographic. Cholesterol gallstone preva-
lence approaches 50% to 75% in certain Native American
populations—the Pima, Hopi, and Navajos—whereas
pigment stones are rare; the prevalence seems to be
related to biliary cholesterol hypersecretion.
• Heredity. In addition to ethnicity, a positive family history
imparts increased risk, as do a variety of inborn errors of
metabolism such as those associated with impaired bile
salt synthesis and secretion.
• Environment. Estrogenic influences, including oral con-
traceptives and pregnancy, increase hepatic cholesterol
uptake and synthesis, leading to excess biliary secretion of
cholesterol. Obesity, rapid weight loss, and treatment with
the hypocholesterolemic agent clofibrate also are strongly
associated with increased biliary cholesterol secretion.
• Acquired disorders. Any condition in which gallbladder
motility is reduced predisposes to gallstones, such as preg-
nancy, rapid weight loss, and spinal cord injury. In most
cases, however, gallbladder hypomotility is present without
obvious cause.

MORPHOLOGY Figure 15–36 Pigmented gallstones. Several faceted black gallstones are
present in this otherwise unremarkable gallbladder removed from a
Cholesterol stones arise exclusively in the gallbladder and patient who had a mechanical mitral valve prosthesis, leading to chronic
consist of 50% to 100% cholesterol. Pure cholesterol intravascular hemolysis.
stones are pale yellow; increasing proportions of calcium
carbonate, phosphates, and bilirubin impart gray-white to
black discoloration (Fig. 15–35). They are ovoid and firm;