Differential diagnosis of cholangiocarcinoma and IgG4-related sclerosing cholangitis by fluorescence in situ hybridization using transpapillary forceps biopsy specimens.

BACKGROUND: Fluorescence in situ hybridization (FISH) of cytology specimens has been used to diagnose biliary strictures. However, the usefulness of FISH for differentiating between cholangiocarcinoma (CCA) and IgG4-related sclerosing cholangitis (IgG4-SC) has not been evaluated in forceps biopsy specimens.

METHODS: We retrospectively reviewed 74 specimens obtained by transpapillary forceps biopsy between 2008 and 2015 from 49 consecutive patients with CCA and 25 with IgG4-SC. Specimens were considered positive for malignancy by FISH with UroVysion® if at least five cells exhibited polysomy (a gain of two or more in chromosomes 3, 7, or 17).

RESULTS: A total of 27 (55.1%) patients with CCA, but none of the patients with IgG4-SC, were positive for malignancy by FISH. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FISH for the diagnosis of CCA were 55.1%, 100%, 100%, 53.2%, and 70.3%, respectively. The complementary use of FISH increased the sensitivity of hematoxylin-and-eosin (H&E) staining from 69.4% to 77.6%; the specificity was not reduced when either H&E or FISH was positive.

CONCLUSIONS: The use of FISH in the analysis of forceps biopsy specimens might be one option to differentiate CCA from IgG4-SC.