Diagnostic Pearls and Pitfalls in the Evaluation of Small Biopsies From the Bile Duct and Ampulla.

Context.—: Histopathologic evaluation of bile duct and ampullary biopsies can be challenging. Biopsies from these sites are often tiny, scant, and/or fragmented. When assessing these biopsies, there is significant overlap between reactive atypia and malignancy, in situ precursor lesions can be misinterpreted as malignancy, and nonprimary tumors can mimic primary disease.

Objective.—: To provide diagnostic pearls and pitfalls in the evaluation of small biopsies from the biliary tract.

Data sources.—: Literature review of published studies and the author's own observations.

Conclusions.—: Because the procedures for obtaining specimens from the bile duct and ampulla are invasive, pathologists need to try to make definitive diagnoses. Diagnostic clues/pearls, ancillary studies, and recognition of various pitfalls can assist in providing accurate and confident diagnoses.