Brown lithiasis material is seen completely occluding the duct.
The surrounding tissue is affected by a brisk collection of foamy macrophages and chronic inflammation, with loss of epithelium.
Admixed within the inflammation is also an acute component, which overlies some peripheral sclerosis.
The ductal epithelium is only partly intact, with a marked inflammatory infiltrate.
The duct wall shows chronic changes with randomly situated dense collagenous bands with intervening inflammation.
Choledocholithiasis is the result of an obstructing stone within the common bile duct. Most stones that migrate down the duct from the gallbladder do not harbor bacteria and are not associated with infected bile. In contrast, most stones that form within the duct are of the brown pigment type and are frequently associated with infectious organisms, most often E. Coli and B. fragilis. Brown pigmented gallstones contains unconjugated bilirubin, which increases in infection -- these types of stones are more frequently seen in certain Asian rural regions (Kumar).
Obstruction most often leads to bacterial infection (cholangitis) and associated symptoms include intermittent abdominal pain, fever, and jaundice (Charcot's triad). Elevated WBC counts and abnormal liver function tests (usually alkaline phosphatase)may also be present.
Kumar V, Abbas AK, Fausto N. Robbins and Cotran Pathologic Basis of Disease. 7th Ed. Philadelphia, PA: Elsevier; 2005: 929, 933.