Cytologic Diagnosis of Biliary Strictures: FISH or Cut the Sensitivity Rate?

Morpho-molecular approach (NGS plus digital PCR) in diagnosis of malignant biliary strictures

Objective

To analyze the diagnostic accuracy and feasibility of digital-PCR (dPCR) combined with next-generation sequencing (NGS) in the ERCP-guided histological diagnosis of biliary strictures to overcome the issue represented by the scarcity of sampled material.

Methods

Twenty-two prospective patients were included, and submitted to ERPC-guided biopsy or biliary resection. By histopathological analysis plus fluorescence in situ hybridization (FISH) for chromosomes 3, 7, and 17 aneuploidies, 8 cases (36.4%) were malignant, and 14 cases (63.6%) were negative. NGS was performed on paraffin-embedded tissue by a laboratory-developed panel allowing the analysis of hot-spot regions in 28 genes. Digital PCR (dPCR) was performed by QuantStudio™ AbsoluteQ™ solid dPCR and the copy-number variation (CNV) of the chromosomes 3, 7, and 17 analysed.

Results

At dPCR, 1 case showed aneuploidy of chromosome 3, and 2 cases of both chromosomes 3 and 7. These 3 cases all belonged to the positive group (p = 0.014). At NGS, 6 cases showed at least one mutated gene, all in the positive group (p < 0.001). The 3 cases showing aneuploidy at dPCR also showed mutations at NGS. Basing on these observations, we can propose a diagnostic algorithm: dPCR can be applied first, allowing a diagnosis of malignancy in one working day if aneuploidies are observed. In the case of negative dPCR, a "second-line" NGS is performed on the same extracted material.

Conclusions

The implementation of dPCR allowed the identification of nearly 40% of positive cases in just one working day. In cases of negative dPCR, the NGS procedure can start on the same extracted nucleic acid used for dPCR, requiring more time, but reaching a 75% sensitivity. More studies are required to identify other more sensitive and specific dPCR targets, but even if our algorithm does not increase diagnostic accuracy, the possibility of avoiding FISH and reaching a diagnosis in a more time- and money-saving fashion might be an important step.

Diagnostic Accuracy Performance of Fluorescence In Situ Hybridization (FISH) for Biliary Strictures: A Systematic Review and Meta-Analysis

Background and Aims: This systematic review and meta-analysis aims to compare the performance of UroVysion® FISH based on the different definitions of a positive result used in published literature with the goal of determining the optimal FISH definition for detecting pancreaticobiliary malignancy. Methods: A systematic literature search identified studies from database inception to Sept 2024 that evaluated the diagnostic performance of FISH in determining malignancy among patients with biliary strictures. All thresholds for positive FISH, as defined by the individual study, were included in this review. Subgroup analysis was performed based on the definitions of positive FISH as follows: (1) polysomy only; (2) polysomy, tetrasomy, or trisomy; and (3) polysomy or 9p deletion. Results: Eighteen studies comprising 2516 FISH specimens were analyzed, including 1133 (45.0%) with malignancy. Using a threshold for positivity as defined in individual studies, the overall sensitivity of FISH was 57.6% (95% confidence interval [CI], 49.4-65.4%), and the overall specificity was 87.8% (95% CI, 79.2-93.2%). Subgroup analysis showed that polysomy as the threshold for positive FISH yielded a sensitivity of 49.4% (95% CI, 43.2-55.5%), with an increased specificity of 96.2% (95% CI, 92.7-98.1%), while polysomy + tetrasomy/trisomy as positive FISH resulted in an increased sensitivity of 64.3% (95% CI 55.4-72.2%) but a decreased specificity of 78.9% (95% CI 64.4-88.5%). The addition of 9p deletion to polysomy as the criteria for a positive test resulted in a non-significant increase in sensitivity (54.7% (95% CI 42.4-66.5%) while maintaining specificity (95.1% (95% CI 84.0-98.6%). Conclusions: Based on these findings, polysomy only or polysomy/9p deletion should be considered as the criterion for defining a positive FISH test to improve diagnostic sensitivity while maintaining high specificity.

Precision Medicine in Cytopathology

Over the last decade, cancer diagnostics has undergone a notable transformation with increasing complexity. Minimally invasive diagnostic tests, driven by advanced imaging and early detection protocols, are redefining patient care and reducing the need for more invasive procedures. Modern cytopathologists now safeguard patient samples for vital biomarker and molecular testing. In this article, we explore ancillary testing modalities and the role of biomarkers in organ-specific contexts, underscoring the transformative impact of precision medicine. Finally, the advent of more than 80 Food and Drug Administration-approved predictive biomarkers signals a new era, guiding cancer care toward personalized and targeted strategies.

Diagnostic pitfalls and the value of fluorescence in situ hybridization as an adjunct to cytologic evaluation of bile duct brushings in patients with primary sclerosing cholangitis

BACKGROUND

Primary sclerosing cholangitis (PSC) can present diagnostic difficulties on bile duct brushings as cytologic features mimicking adenocarcinoma may exist. This study evaluates the role of fluorescence in-situ hybridization (FISH) as an adjunct to cytologic evaluation.

METHODS

From January 1, 2020, through December 31, 2021, 308 bile duct brushings were processed of which 34 (11%) were malignant, 25 (8%) were suspicious, 36 (12%) were atypical, 204 (66%) were negative and 10 (3%) were nondiagnostic. Follow-up biopsies/resections were performed in the 95 cases with diagnostic cytology (atypical/suspicious/malignant) of which 12 (13%) showed primary sclerosing cholangitis and form the basis of this study. Cytologic, histologic and FISH findings are presented and discussed.

RESULTS

Of the 12 bile duct brushings 4 (34%) were positive/suspicious for adenocarcinoma and 8 (66%) showed atypical epithelial cells. FISH was positive in 2/4 positive/suspicious brushings and negative in the remaining 2 brushings. Histologic findings confirmed the FISH results. The cytologic features of the 2 false positive cases overlapped those of adenocarcinoma. Two of the 8 bile duct brushings with atypical epithelial cells were positive/suspicious for adenocarcinoma on FISH analysis; findings confirmed on histologic follow-up. The remaining 8 patients underwent surveillance for the development of adenocarcinoma with repeat bile duct brushings, FISH analysis and biopsies, each of which has been negative to date.

CONCLUSION

FISH, as an adjunct to the cytologic evaluation of bile duct brushings from patients with PSC, plays a role in improving diagnostic accuracy and serves as a surveillance tool for the potential development of adenocarcinoma.

The Role of Fluorescence In Situ Hybridization in Pancreatobiliary Brushing Cytology: A Large Retrospective Review with Histologic Correlation

(1) Background: Although the specificity of brush cytology for the detection of malignant pancreaticobiliary strictures is high, its sensitivity is low. Fluorescence in situ hybridization (FISH) can be used to detect chromosomal aneuploidy in biliary brushing specimens, and when used as an adjunct to routine cytology, it significantly improves diagnostic sensitivity. (2) Methods: We searched our laboratory information system to identify all bile duct brush cytology cases with follow-up surgical pathology between January 2001 and September 2019. Cytologic diagnoses were classified as negative, atypical, suspicious, or malignant. Correlated surgical pathological diagnoses were classified as benign or malignant. FISH test results were obtained for a subset of cytology cases with concurrent FISH testing, and the sensitivity, specificity, positive predictive value, and negative predictive value in identifying malignancy for cytology alone, FISH alone, and combined cytology and FISH were calculated. (3) Results: A total of 1017 brushing cytology cases with histologic correlation were identified. A total of 193 FISH tests were performed concurrently with cytological specimens. Malignant diagnoses were identified in 623 of 1017 patients, while 394 patients had benign strictures. The sensitivity, specificity, positive predictive, and negative predictive rate were 65%, 78%, 83%, and 49% for cytology alone; 72%, 67%, 63%, and 68% for FISH alone; and 85%, 42%, 60%, and 74% for combined cytology and FISH, respectively. Among FISH-positive cases, the risk of malignancy for polysomy was 82% and 32% for trisomy. (4) Conclusions: FISH improves the sensitivity and negative predictive rate of bile duct brush cytology. The combination of cytology and FISH has increased the sensitivity from 65% to 85% and the negative predictive rate from 49% to 74% when compared to cytology alone. A patient with a polysomy FISH result had a significantly higher risk of malignancy than a patient with a trisomy 7 result (82% vs. 32%, p < 0.00001).

Impact of trimodality sampling on detection of malignant biliary strictures compared with patients with primary sclerosing cholangitis

BACKGROUND AND AIMS

Malignant biliary strictures can be difficult to diagnose, with up to 20% considered indeterminate after initial tissue sampling. This study aimed to determine the performance characteristics of transpapillary biopsy sampling (TPB) and fluorescence in situ hybridization (FISH) in isolation or in combination with standard brush cytology (BC) in patients who received trimodality sampling for biliary strictures.

METHODS

This single-center retrospective cohort study included patients with biliary strictures undergoing ERCP with trimodality sampling between September 2014 and April 2019. Performance characteristics for each diagnostic test alone and in combination were calculated.

RESULTS

Two hundred four patients underwent trimodality biliary sampling, including 104 (51.0%) with malignancy. The diagnostic sensitivity for malignancy with BC (17.3%) significantly improved with dual modality (BC+FISH, 58.7%; BC+TPB, 40.4%) or trimodality sampling (68.3%; P < .001 for all comparisons). Trimodality sampling improved diagnostic sensitivity for malignancy compared with BC+FISH (P = .002) and BC+TPB (P < .001). There was no statistically significant difference in the sensitivity of trimodality sampling in detecting cholangiocarcinoma (79.7%) compared with pancreatic cancer (62.5%; P = .1). Among 57 patients with primary sclerosing cholangitis (PSC), the sensitivity of detecting biliary malignancy (n = 20) was 20% for BC and significantly improved with the addition of FISH (80%; P < .001) but not with TPB (35.0%; P = .25). Trimodality sampling did not further improve diagnostic sensitivity (85%) over BC+FISH (80%) for malignancy in the setting of PSC (P = 1).

CONCLUSIONS

Trimodality sampling improves the diagnostic sensitivity for the detection of malignant biliary strictures with no significant difference in sensitivity for cholangiocarcinoma compared with pancreatic cancer. However, in patients with PSC, trimodality sampling was not superior to BC+FISH.

Refined pancreatobiliary UroVysion criteria and an approach for further optimization

Pancreatobiliary strictures are a common source of false negatives for malignancy detection. UroVysion is more sensitive than any other method but remains underutilized because of conflicting sensitivities and specificities due to a lack of standardized cutoff criteria and confusion in interpreting results in the context of primary sclerosing cholangitis. We set out to determine the sensitivities and specificities of UroVysion, brushing cytology, forceps biopsies, and fine needle aspiration (FNAs) for pancreatobiliary stricture malignancy detection. A retrospective review was performed of all biopsied pancreatobiliary strictures at our institution over 5 years. UroVysion was unquestionably the most sensitive method and all methods were highly specific. Sensitivity was highest while maintaining specificity when a malignant interpretation was limited to cases with 5+ cells with the same polysomic signal pattern and/or loss of one or both 9p21 signals. Only UroVysion detected the metastases and a neuroendocrine tumor. In reviewing and analyzing the signal patterns, we noticed trends according to location and diagnosis. Herein we describe our method for analyzing signal patterns and propose cutoff criteria based upon observations gleaned from such analysis.

Optimal tissue sampling during ERCP and emerging molecular techniques for the differentiation of benign and malignant biliary strictures

Patients with cholangiocarcinoma have poor survival since the majority of patients are diagnosed at a stage precluding surgical resection, due to locally irresectable tumors and/or metastases. Optimization of diagnostic strategies, with a principal role for tissue diagnosis, is essential to detect cancers at an earlier stage amenable to curative treatment. Current barriers for a tissue diagnosis include both insufficient tissue sampling and a difficult cyto- or histopathological assessment. During endoscopic retrograde cholangiopancreatography, optimal brush sampling includes obtaining more than one brush within an individual patient to increase its diagnostic value. Currently, no significant increase of the diagnostic accuracy for the new cytology brush devices aiming to enhance the cellularity of brushings versus standard biliary brush devices has been demonstrated. Peroral cholangioscopy with bile duct biopsies appears to be a valuable tool in the diagnostic work-up of indeterminate biliary strictures, and may overcome current technical difficulties of fluoroscopic-guided biopsies. Over the past years, molecular techniques to detect chromosomal instability, mutations and methylation profiling of tumors have revolutionized, and implementation of these techniques on biliary tissue during diagnostic work-up of biliary strictures may be awaited in the near future. Fluorescence in situ hybridization has already been implemented in routine diagnostic evaluation of biliary strictures in several centers. Next-generation sequencing is promising for standard diagnostic care in biliary strictures, and recent studies have shown adequate detection of prevalent genomic alterations in KRAS, TP53, CDKN2A, SMAD4, PIK3CA, and GNAS on biliary brush material. Detection of DNA methylation of tumor suppressor genes and microRNAs may evolve over the coming years to a valuable diagnostic tool for cholangiocarcinoma. This review summarizes optimal strategies for biliary tissue sampling during endoscopic retrograde cholangiopancreatography and focuses on the evolving molecular techniques on biliary tissue to improve the differentiation of benign and malignant biliary strictures.

Pancreatic ductal adenocarcinoma and distal cholangiocarcinoma: a proposal of preoperative diagnostic score for differential diagnosis

PURPOSE

The differential diagnosis between primary adenocarcinoma of the pancreas head and distal cholangiocarcinoma remains a clinical challenge. Recent studies have shown important differences in terms of survival between these tumors. Therefore, different treatments should be considered, but the preoperative histological diagnosis is still difficult. Aim of this study is to create a preoperative diagnostic score for differential diagnosis between primary pancreatic adenocarcinoma and primary distal cholangiocarcinoma.

METHODS

One hundred eighty consecutive patients who underwent pancreaticoduodenectomy at Sapienza University of Rome from January 2010 to December 2019 were retrospectively analyzed. Inclusion criteria were pancreatic or biliary histologic origin obtained by definitive postoperative histological examination. Exclusion criteria were diagnosis of ampullary carcinoma, non-ampullary duodenal adenocarcinoma, pancreatic metastasis, and benign disease. One hundred one patients were considered eligible for the retrospective study. Preoperative biological, clinical, and radiological parameters were considered.

RESULTS

CRP > 10 mg/dL (p = 0.001), modified Glasgow Prognostic Score 2 (p = 0.002), albumin < 35 g/L (p = 0.05), CA 19-9 > 230 U/mL (p = 0.001), and Wirsung diameter > 3 mm (p < 0.001) were significant at univariate logistic analysis. Multivariate logistic analysis has shown that parameters independently associated with primary pancreatic adenocarcinoma were CRP > 10 mg/dL (p = 0.012), CA 19-9 > 230 U/mL (p = 0.043), and diameter of the Wirsung > 3 mm (p = 0.005). Through these parameters, a diagnostic score has been developed to predict a primary pancreatic adenocarcinoma when > 1 and a primary distal cholangiocarcinoma when < 1.

CONCLUSION

This feasible and low-cost diagnostic score could have a potential impact to differentiate pancreatic cancer histologic origin and to improve target therapeutic strategy.