Fluorescence In Situ Hybridization in Primary Diagnosis of Biliary Strictures: A Single-Center Prospective Interventional Study

Abstract

Background and aims: Diagnosis of the biliary stricture remains a challenge. In view of the low sensitivity of brush cytology (BC), fluorescence in situ hybridization (FISH) has been reported as a useful adjunctive test in patients with biliary strictures. We aimed to determine performance characteristics of BC and FISH individually and in combination (BC + FISH) in the primary diagnosis of biliary strictures. Methods: This single-center prospective study was conducted between April 2019 and January 2021. Consecutive patients with unsampled biliary strictures undergoing first endoscopic retrograde cholangiopancreatography in our institution were included. Tissue specimens from two standardized transpapillary brushings from the strictures were examined by routine cytology and FISH. Histopathological confirmation after surgery or 12-month follow-up was regarded as the reference standard for final diagnosis. Results: Of 109 enrolled patients, six were excluded and one lost from the final analysis. In the remaining 102 patients (60.8% males, mean age 67.4, range 25-92 years), the proportions of benign and malignant strictures were 28 (27.5%) and 74 (72.5%), respectively. The proportions of proximal and distal strictures were 26 (25.5%) and 76 (74.5%), respectively. In comparison to BC alone, FISH increased the sensitivity from 36.1% to 50.7% (p = 0.076) while maintaining similar specificity (p = 0.311). Conclusions: Dual-modality tissue evaluation using BC + FISH showed an improving trend in sensitivity for the primary diagnosis of biliary strictures when compared with BC alone.

Keywords: ZytoLight FISH probe; brush cytology; first retrograde cholangiopancreatography; fluorescence in situ hybridization; primary diagnosis of biliary strictures.

Figure 1

(A): A tuft of benign ductal epithelial cells with a regular arrangement of polarized uniform nuclei. Hematoxylin–eosin staining (100×). PAP II; (B): A cluster of malignant cells with irregular hyperchromic congested, often angular nuclei with irregular karyomembrane. Hematoxylin–eosin staining (100×). PAP VI.

Figure 1

(A): A tuft of benign ductal epithelial cells with a regular arrangement of polarized uniform nuclei. Hematoxylin–eosin staining (100×). PAP II; (B): A cluster of malignant cells with irregular hyperchromic congested, often angular nuclei with irregular karyomembrane. Hematoxylin–eosin staining (100×). PAP VI.

Figure 2

Upper part of of this figure (positive FISH): Nucleus of a tumor cell with increased number of red, green, and blue signals indicating polysomy of the chromosomes 3, 7, and 17, respectively. The third image summarizes the colors of all signals; round yellow (gold) signals marking CDKN2 (p16) are clearly visible, so deletion of this gene is not present; Lower part of this figure (negative FISH): Three nuclei of benign cells are visible without increased number of signals for chromosomes 3, 7, and 17, respectively, and without CDKN2(p16) deletion.

Figure 3

Study flow chart.