Significance of atypia in pancreatic and bile duct brushings: Follow-Up analysis of the categories atypical and suspicious for malignancy

The World Health Organization Reporting System for Pancreaticobiliary Cytopathology: Review and Comparison to the Papanicolaou Society of Cytopathology System

CONTEXT.—

The World Health Organization (WHO) Reporting System for Pancreaticobiliary Cytopathology (WHO System) is the product of a joint venture between the World Health Organization, the International Academy of Cytology, and the International Agency for Research on Cancer. The WHO System revises the Papanicolaou Society of Cytopathology System for Reporting Pancreaticobiliary Cytology (PSC System) and replaces the 6-tiered system with a 7-tiered system.

OBJECTIVE.—

To explain the WHO System and the differences with the PSC System.

DATA SOURCES.—

The WHO System and the PSC System of Reporting Pancreaticobiliary Cytopathology.

CONCLUSIONS.—

The diagnostic categories of the WHO System are "Insufficient/Inadequate/Nondiagnostic"; "Benign (Negative for Malignancy)"; "Atypical"; "Pancreaticobiliary Neoplasm, Low Risk/Low Grade (PaN-Low)"; "Pancreatic Neoplasm, High Risk/High Grade (PaN-High)"; "Suspicious for Malignancy"; and "Malignant." In the WHO System, the "benign" category includes both nonneoplastic and neoplastic lesions, so the "Neoplastic: Benign" category of the PSC system has been eliminated. Low-grade malignancies, pancreatic neuroendocrine tumors (PanNETs), and solid-pseudopapillary neoplasm (SPN) classified as "Neoplastic: Other" in the PSC System are classified as "Malignant" in the WHO System, leaving in the "Neoplasm" category intraductal lesions, which are divided into 2 new diagnostic categories: "Pancreaticobiliary Neoplasm (PaN)-Low Risk/Grade" and "PaN-High Risk/Grade." As with the PSC System, the WHO System advocates close correlation with imaging and encourages incorporation of ancillary testing into the final diagnosis, such as biochemical (carcinoembryonic antigen [CEA] and amylase) and molecular testing. The WHO System includes risk of malignancy per category, and reporting and diagnostic management options that recognize the variations in resources of low- and middle-income countries.

Verifying a novel bile cytology scoring system

BACKGROUND

The scoring system for bile cytology (SSBC) aims to improve bile cytology diagnostic accuracy. Here, the practicality of SSBC was verified by multiple cytotechnologists.

METHODS

Bile cytological specimens were evaluated by 24 cytotechnologists using SSBC. The samples were assessed before using the SSBC (first-time assessment) according to three categories: benign, indeterminate, and malignant. A first scoring evaluation (FSE) was then performed using SSBC; each item in the scoring system was classified as present or absent. After distributing an instruction sheet with diagnostic criteria, a second scoring evaluation (SSE) was performed using SSBC. Each method was evaluated using diagnostic accuracy and interobserver and intraobserver agreement.

RESULTS

Several samples were assessed as indeterminate in the first-time assessment. Although the specificity of the SSE improved, the sensitivity and accuracy decreased compared with those of the FSE. The overall interobserver agreement was fair for all parameters, including abnormal chromatin, irregular internuclear distances, irregularly overlapped nuclei, irregular cluster margins, and final evaluation in the FSE and SSE. The final evaluation by histological type exhibited slight agreement for well-differentiated tubular adenocarcinoma and almost perfect agreement for poorly differentiated tubular adenocarcinoma in the FSE and SSE. For moderately differentiated tubular adenocarcinoma, agreement was moderate in the FSE and fair in the SSE. For cholangitis, a slight agreement was observed in the FSE, which improved to fair in the SSE.

CONCLUSIONS

Although the SSBC is expected to improve specificity, there exists ambiguity regarding SSBC criteria and interindividual assessment differences. Therefore, the objective assessment method should be revised.

The World Health Organization Reporting System for Pancreaticobiliary Cytopathology: Overview and Summary

The recently published WHO Reporting System for Pancreaticobiliary Cytopathology (World Health Organization [WHO] System) is an international approach to the standardized reporting of pancreaticobiliary cytopathology, updating the Papanicolaou Society of Cytopathology System for Reporting Pancreaticobiliary Cytology (PSC System). Significant changes were made to the categorization of benign neoplasms, intraductal neoplasms, mucinous cystic neoplasms, and malignant neoplasms considered low grade. Benign neoplasms, such as serous cystadenoma, categorized as Neoplastic: benign in the PSC system, are categorized as Benign/negative for malignancy in the WHO system. Pancreatic neuroendocrine tumor, solid-pseudopapillary neoplasm, and gastrointestinal stromal tumor, categorized as Neoplastic: other in the PSC system, are categorized as Malignant in the WHO System in accord with their classification in the 5th edition WHO Classification of Digestive System Tumours (2019). The two new categories of Pancreaticobiliary Neoplasm Low-risk/grade and Pancreaticobiliary Neoplasm High-risk/grade are mostly limited to intraductal neoplasms and mucinous cystic neoplasms. Low-risk/grade lesions are mucinous cysts, with or without low-grade epithelial atypia. High-risk/grade lesions contain neoplastic epithelium with high-grade epithelial atypia. Correlation with clinical, imaging, and ancillary studies remains a key tenet. The sections for each entity are written to highlight key cytopathological features and cytopathological differential diagnoses with the pathologist working in low resource setting in mind. Each section also includes the most pertinent ancillary studies useful for the differential diagnosis. Sample reports are provided for each category. Finally, the book provides a separate section with risk of malignancy and management recommendations for each category to facilitate decision-making for clinicians.

Combining brushing cytology with simultaneous vacuum aspiration in suspicious biliopancreatic malignancies: A multicenter propensity score-matched study (with video)

BACKGROUND

Brush cytology during endoscopic retrograde cholangiopancreatography (ERCP) is a standard approach in diagnosing biliopancreatic strictures, with yet unsatisfying sensitivity.

AIMS

We brought additional simultaneous vacuum aspiration to brushing process and re-evaluate the diagnostic performance.

METHODS

This multi-centered retrospective study was conducted in three tertiary centers. Consecutive patients with biliopancreatic strictures were identified. The patients were divided into two arms: the conventional arm (CA) receiving general brushing approach, and the modified arm (MA) being treated with additional vacuum aspiration when performing bushing. The 1:1 propensity-score matching was implemented to tackle the selective biases.

RESULTS

A total of 555 patients were identified and 200 patient pairs (193 males, 207 females, with a mean age of 68.1 ± 13.1 years.) fell into the ultimate evaluation. A final diagnosis of malignant stricture was established in 243 patients. The diagnostic yield of the MA group was substantially better than that of the CA group, whether "suspicious malignancies" were considered malignancies or not. The rates of sensitivity, specificity and accuracy were 46.2%, 100%, 68.0% in the MA group, and 15.3%, 98.7%, and 47.0% in the CA group respectively.

CONCLUSIONS

Brushing accompanied by simultaneous vacuum aspiration at ERCP improves the diagnostic yield in suspicious biliopancreatic malignancies.

The rationale for the development and publication of the World Health Organization reporting systems for cytopathology and a brief overview of the first editions of the lung and pancreaticobiliary systems

The International Academy of Cytology has joined with the International Agency for Research on Cancer and the World Health Organization (WHO) to develop international systems for reporting the cytopathology of lung, pancreas and biliary tract, lymph nodes, soft tissue, liver, breast, and kidney and adrenal gland. The WHO recently published the reporting systems for lung and pancreaticobiliary cytopathology. The objectives of this collaboration are to standardize the reporting of cytopathology; improve the quality of reporting by establishing the key diagnostic cytopathological features of entities and neoplasms; provide detailed best-practice guidelines in sampling techniques, specimen handling and processing, and the use of ancillary techniques; and facilitate communication between cytopathologists and clinicians to improve patient care. Each WHO system has defined specific categories and terminology for reporting cytopathology, and each category has an estimated risk of malignancy as far as the current literature allows and a suggested diagnostic management algorithm to assist clinicians. The WHO systems recognize that local medical and pathology infrastructure will vary, particularly in low-income and middle-income countries, and the WHO systems and their diagnostic management recommendations have been developed to allow them to be applied worldwide in all resource settings. The process of the selection of editors and authors and the writing and editing responsibilities has used the same model as that used for the fifth edition WHO Classification of Tumours, to which the WHO cytopathology systems are directly linked. This review provides the rationale and history of this joint International Academy of Cytology, International Agency for Research on Cancer, and WHO cytopathology project and a brief overview of the WHO reporting systems for lung and pancreaticobiliary cytopathology.

Diagnostic sensitivity and risk of malignancy for bile duct brushings categorized by the Papanicolaou Society of Cytopathology System for reporting pancreaticobiliary cytopathology

BACKGROUND

The Papanicolaou Society of cytopathology developed a six-category system for pancreaticobiliary cytology specimens. Each category is associated with a definition, diagnostic criteria, estimated risk of malignancy and management recommendations. Risks of malignancy are well defined for specimens obtained by fine-needle aspiration but are less well defined for brushing specimens.

METHODS

Diagnoses of 232 brushing specimens of the pancreatic and bile ducts were correlated with diagnoses from subsequent surgical or cytologic specimens. Sensitivity for the brushing technique was calculated. Risk of malignancy was calculated for each category using the original definitions for nondiagnostic and negative categories and for those of a modified system.

RESULTS

Diagnostic sensitivity was 60%-64%. Risk of malignancy for the nondiagnostic, negative, atypical, suspicious for malignancy, and malignant categories was 28%, 28%, 61%, 91%, and 91%, respectively, when the original category definitions were used.

CONCLUSIONS

Diagnostic sensitivity for duct brushings is low in comparison to fine-needle aspiration. Risk of malignancy is comparable to that of needle aspiration for the negative, atypical and suspicious categories but lower for the malignant category. There is a stepwise increase in malignancy risk as one moves from the negative to the atypical to the suspicious for malignancy categories.

Atypical cells in fine needle aspiration biopsies of pancreas: Causes, work-up, and recommendations for management

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is a sensitive and specific method for diagnosing cancer in solid pancreatic masses. However, some cases receive indeterminate atypical diagnoses, which creates management dilemmas. In the 2014 Papanicolaou Society of Cytopathology (PSC) standardized guidelines for pancreatobiliary cytology, specimens in the "Atypical" category show a spectrum of architectural and/or cellular changes beyond normal or reactive, but, quantitatively or qualitatively, insufficient for classification as neoplastic (benign/other), suspicious or positive for malignancy. Implementation of the PSC system decreased atypical diagnoses, particularly for cystic lesions, and redistributed many cases into benign and neoplastic categories. Because no set cytologic criteria exist for the "Atypical" category there is wide variability in its use, and its frequency ranges from 0%-16% (mean 6%). It consists of a heterogeneous mix of cases that occur because of preanalytic, lesion-specific (low cellularity, necrosis, cystic, reactive and premalignant changes), to pathologist-dependent factors (experience, expertise, training and institutional case volume). Outcomes of atypical diagnoses in solid pancreatic masses range from benign to premalignant and malignant and include reactive atypia in pancreatitis, well differentiated adenocarcinoma, and non-ductal malignancies. The associated risk of malignancy (ROM) ranges from 28%-100%, with an overall intermediate ROM in large-scale studies. Cytopathologists and institutions should monitor and keep their personal and/or laboratory's atypical rates low by judiciously using rapid onsite evaluation, ancillary studies, consensus or expert review, as well as correlation with clinical and radiologic findings. Early repeat EUS-FNA is indicated for unresolved cases.

Application of enhancer of zeste homolog 2 immunocytochemistry to bile cytology

BACKGROUND

Bile cytology has low diagnostic sensitivity and requires ancillary techniques. This study assessed the utility of enhancer of zeste homolog 2 (EZH2) immunocytochemistry (ICC) in bile cytology.

METHODS

A total of 141 bile cytology specimens from 141 patients were evaluated retrospectively. Papanicolaou-stained slides were immunostained with an antibody to EZH2. After calculation of the EZH2 labeling index (LI), the cutoff value was determined via receiver operating characteristic curve analysis. Cytological performance with and without EZH2 ICC was evaluated with reference to the final diagnosis.

RESULTS

The area under the curve for the EZH2 LI was 0.955, and the cutoff value for identifying benign bile samples versus malignant ones was 24.0%. The sensitivity and specificity values for malignancy were 53.4% and 100% for routine cytology only, 89.0% and 95.7% for EZH2 ICC only, and 89.8% and 95.7% for a combination of routine cytology and EZH2 ICC. The sensitivities of EZH2 ICC only and a combination of routine cytology and EZH2 ICC were significantly improved in comparison with routine cytology only (P < .001). EZH2 ICC alone had a sensitivity of 68.0% and a specificity of 85.7% in bile samples with atypical cytology, a sensitivity of 87.0% in samples that were suspicious for malignancy, and a sensitivity of 85.7% and a specificity of 100% in samples that were negative for malignancy.

CONCLUSIONS

EZH2 ICC improved the diagnostic sensitivity for pancreatobiliary adenocarcinoma in bile cytology. This method is particularly meaningful in samples of indeterminate cytology and may be useful as an initial assessment to ensure that no cancer cells are missed.

Effect of single operator cholangioscopy on accuracy of bile duct cytology

INTRODUCTION

This is the first study to evaluate the accuracy of bile duct brushings since the introduction of single operator cholangioscopy SpyGlass DS system in 2015. The primary aim of our study was to compare the accuracy of cytology brushings against biopsies obtained at endoscopic retrograde cholangiopancreatography (ERCP) and cholangioscopy.

METHOD

A retrospective search for bile duct brushing specimens was performed and the charts reviewed. The gold standard for definitive diagnosis of malignancy was surgical tissue or compelling clinical evidence of malignancy. Definite negative diagnosis relied on lack of clinical/imaging features of malignancy on follow-up.

RESULTS

There was no significant difference in diagnostic accuracy of cytology specimens obtained at different procedures. Overall sensitivity for all methods was 59%, specificity 90% and accuracy of 82%. Notably, all four false-positive cases except for one were from patients with primary sclerosing cholangitis or primary biliary sclerosis. There was no significant difference in sensitivity or specificity between biopsies procured by the two methods. The combined biopsy sensitivity for all modalities was 44% with a specificity of 100%. There was 70% concordance between cytology and biopsy cases. The overall specificity and sensitivity of the combined cytology and biopsy result was 85% and 65.3%, respectively. Ranking of factors that predict clinical diagnosis shows cytology results to surpass other parameters including pancreatic mass, age and stenosis length. Similarly, the presence of two cell populations and three-dimensional clusters was not nearly as predictive of malignancy as single malignant cells.

CONCLUSION

Biliary brush cytology specimens performed better than biopsies irrespective of whether they are procured during ERCP or cholangioscopy. The combination of cytology and biopsy had the best accuracy than either one alone.

Ethanol-based fixation is superior to conventional brush cytology in the evaluation of indeterminate biliary strictures by endoscopic retrograde cholangiography

The aim of this study was to compare the diagnostic yield of conventional cytology (CC) with ethanol-based fixation, a cytological analysis using an ethanol based fixative system including a cell block procedure (EBF) to evaluate indeterminate biliary strictures (IBStr). We also compared additionally taken fluorescence-guided forceps biopsies (FB) with EBF concerning a potential additive diagnostic benefit.Early detection and accurate diagnosis are crucial for patients with suspected carcinoma within the biliary tree to preserve curative treatment options but diagnostics and patient care in the evaluation of IBStr are still challenging. ERC-guided brush cytology is the gold standard of nonsurgical evaluation of IBStr. However, accuracy is generally low. New specimen processing's are needed to higher the diagnostic yield in the evaluation of IBStr.We performed a retrospective evaluation in 404 patients referred for further diagnosis of IBStr. Gold standard was defined as surgically obtained histology or patient follow-up of at least 1 year to diagnose or exclude malignancy.Three hundred thirty-four patients were included into the final analysis. One hundred seventy-two strictures were malignant, 162 strictures benign. One hundred seventeen specimens were evaluated by CC, 217 processed by EBF. EBF performed significantly better in terms of sensitivity (24.6% vs 60%, P < .001) and accuracy (59.0% vs 75.1%, P = .006). Fifty-eight FB were additionally taken and showed a numerically improved sensitivity compared to EBF alone (80% vs 62.9%, P = .19).EBF is a simple and inexpensive technique that substantially improved sensitivity and accuracy in the evaluation of IBStr. FB specimen did not significantly improve diagnostic yield.

Factors Impacting the Performance Characteristics of Bile Duct Brushings: A Clinico-Cytopathologic Analysis of 253 Patients

Context.—

Literature on factors impacting bile duct brushings (BDBs) performance characteristics remain limited.

Objective.—

To capture the current state of daily practice with BDB sign-out.

Design.—

Two hundred fifty-three of 444 BDBs signed out by more than 7 cytopathologists, with histopathologic and/or clinical follow-up of at least 18 months, were examined.

Results.—

One hundred thirty-five of 253 BDBs (53%) had histologically confirmed malignancies, 22 (9%) had cancer-related deaths, and 96 (38%) were benign. Cytologic diagnoses in the 444 BDBs were nondiagnostic (11 [2.5%]), negative (284 [64%]), atypical (62 [13.9%]), suspicious (34 [7.7%]), and malignant (53 [11.9%]). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of malignancy detection were 35%, 100%, 100%, 58%, and 66%, respectively. When atypical, suspicious, and malignant (ASM) categories were combined, sensitivity increased (58%), specificity and PPV dropped (97%), and accuracy increased (73%). Carcinoma type (bile-duct versus pancreatic-ductal) had no effect on accuracy (P = .60) or diagnostic class (P = .84), nor did time of performance (first 7.5 versus latter 7.5 years, P = .13). Interestingly, ThinPrep + cell block (n = 41) had higher sensitivity (61%) and lower specificity (80%) than ThinPrep only (versus 51% and 100%, respectively). Sensitivity and specificity were higher (47% and 100%) in nonstented than stented specimens (59% and 97%). Relative risk of malignancy for “suspicious” (2.30) and “atypical” (2.28) categories was lower but not very different from that of “malignant” category (2.41).

Conclusions.—

Bile duct brushings had fairly low sensitivity but high specificity and PPV with no false positives. Sensitivity almost doubled and specificity dipped minimally when ASM categories were combined, highlighting the need for better classification criteria for atypical/suspicious cases. Higher specificity, PPV, NPV, and accuracy but lower sensitivity in stented BDBs suggest that they be called malignant only when evidence is overwhelmingly convincing.

Papanicolaou Society of Cytopathology new guidelines have a greater ability of risk stratification for pancreatic endoscopic ultrasound-guided fine-needle aspiration specimens

The Papanicolaou Society of Cytopathology has recently proposed a standardized terminology and nomenclature guidelines for pancreatic cytology. However the risk of malignancy associated with the new guidelines has been scarcely studied. In this study, a series of pancreatic cytology cases obtained by endoscopic ultrasound-guided fine-needle aspiration from 294 Chinese patients were retrospectively re-categorized into six categories according the new guidelines. The risks of malignancy were 18.1% for “negative,” 20.0% for “neoplastic,” 57.1% for “nondiagnostic,” 69.2% for “atypical,” 87.5% for “suspicious,” and 100.0% for “positive” respectively. The area under the receiver operating characteristic curve was 0.93 (95% Confidence Interval, 0.90-0.96), which was significantly higher than that associated with old classification system (0.82; 95% Confidence Interval, 0.77-0.87) conventionally used in China. Our investigation demonstrated that the new guidelines have a greater ability of risk stratification than the old classification system conventionally used in China. This may be helpful in giving better predictions of malignancy, thus leading to more personalized treatment strategies.

Bile duct brushing cytology: Cytohistologic/fine-needle aspiration correlation and diagnostic pitfalls

INTRODUCTION

Bile duct brushings are a mainstay in the work-up of patients who present with clinical findings of pancreaticobiliary disease. This study presents the University of Wisconsin Hospital and Clinics Cytopathology Laboratory's experience over a 10.5-year period with histologic and fine-needle aspiration (FNA) correlation.

MATERIALS AND METHODS

From January 1, 2005, through June 30, 2015, 676 bile duct brushings were processed, of which 408 (60%) were negative, 84 (12%) were atypical, 65 (10%) were suspicious, and 119 (18%) were malignant. Histologic and FNA follow-up was available in 285 (42%) of the cases and forms the basis of this study.

RESULTS

There were 59 (21%) positive, 38 (13%) suspicious, 54 (19%) atypical, and 134 (47%) negative bile duct brushings with follow-up. Of the 59 positive cases, 57 (97%) were malignant and 2 (3%) were negative on histologic/FNA follow-up. Thirty-three (87%) of the suspicious brushing were malignant on follow-up and 5 (13%) were negative; 43 (80%) of the atypical brushings were malignant and 11 (20%) were negative; and 94 (70%) of the negative brushings were malignant and 40 (30%) were negative on histologic/FNA follow-up. The sensitivity was 38%; specificity, 95%; positive predictive value, 97%; negative predictive value, 30%.

CONCLUSIONS

Bile duct brushing cytology is highly specific in the detection of malignant pancreatobiliary lesions with few false positives, but has low sensitivity with many false negatives.

Monocentric study of bile aspiration associated with biliary brushing performed during endoscopic retrograde cholangiopancreatography in 239 patients with symptomatic biliary stricture

BACKGROUND

The cytologic diagnosis obtained by brushing or biopsy in malignant biliary strictures is considered to be highly specific but poorly sensitive. The diagnostic association of biliary brushing and bile exfoliate cytology has been suggested but is rarely performed in clinical practice. The objective of this study was to assess the diagnostic performance of bile aspiration associated with biliary brushing during therapeutic endoscopic retrograde cholangiopancreatography (ERCP).

METHODS

From 2004 to 2009, 239 consecutive patients who underwent ERCP were included in the study. The biliary strictures were considered clinically benign in 26% of patients, uncertain in 25%, and malignant in 49%. The 298 cytologic samples collected were divided in 3 groups: bile aspiration alone (26%), biliary brushing alone (20%), and bile aspiration combined with brushing (54%). The definitive diagnosis of malignancy was obtained by biopsy, surgery, and fine-needle aspiration or was determined by an unfavorable disease course.

RESULTS

The cytologic diagnoses were as follows: 149 samples were benign (50%), 114 were malignant (38%), 34 had atypia (12%), and 1 had no diagnostic value. The procedure output values were as follows: for bile aspiration alone, sensitivity was 56.4%, specificity was 93.9%, the positive predictive value (PPV) was 91.7%, and the negative predictive value (NPV) was 64.6%; for brushing alone, sensitivity was 62.5%, both specificity and the PPV were 100%, and the NPV was 73%; and, for bile aspiration and brushing combined, sensitivity was 81%, both specificity and the PPV were 100%, and the NPV was 75%.

CONCLUSIONS

For patients who have symptomatic biliary stricture, bile aspiration during ERCP is a simple and safe procedure. Bile aspiration combined with brushing significantly increases the yield of cytology for malignant biliary tumors (sensitivity, 81%), particularly in cholangiocarcinomas. Cancer Cytopathol 2016;124:330-9. © 2015 American Cancer Society.

Strategies for improving diagnostic accuracy of biliary strictures

BACKGROUND

Brush cytology is the initial intervention when evaluating biliary strictures. Biliary brush cytology is known for its low sensitivity (but high specificity) and may be accompanied by biopsies and/or fluorescent in situ hybridization (FISH) to improve diagnostic yield. This study aimed to identify features to enhance cytological sensitivity, and assess which sampling method(s) improve identification of pancreatobiliary adenocarcinomas (PBCa).

METHODS

Seventy-three biliary stricture cases were retrieved (38 PBCa and 35 control benign strictures). Biliary brushings, FISH, and biopsies were reviewed. Cytology specimens were evaluated for cellularity and presence of drunken honeycomb (DH), loosely cohesive clusters of round cells (LCCRC), large atypical cells with foamy cytoplasm (LACF), and single vacuolated malignant cells (SCs). Biopsies were examined for the presence of stromal invasion (SI).

RESULTS

Biliary brushings were scantly cellular in 47.4% of PBCa and 51.4% of controls, resulting in 69.6% nondiagnostic/false-negative cytology diagnoses. DH, LACF, and SCs were significantly associated with adenocarcinoma (P < .00001, .0033, and .00002, respectively). By univariate analysis, SCs and LACF were predictors of malignancy in brushings (P = .0002 and .05). By multivariate analysis, only SCs were predictive of malignancy (P = .002). SI facilitated the diagnosis in 9 biopsies. Sensitivity/specificity of brush cytology, FISH, and biopsy were 39.5%/94.3%, 63.9%/94.3%, and 84.2%/100%, respectively.

CONCLUSIONS

The low sensitivity of biliary brushings results from limited cellularity. Identification of LACF, DH, and SCs improves sensitivity. Sampling of stromal tissue may facilitate PBCa diagnosis. Concurrent biopsies and FISH are helpful in enhancing the diagnostic yield of PBCa.