Malignant biliary stenosis: conventional cytology versus DNA image cytometry

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.

The value of DNA image cytometry combined with brush routine cytology in diagnosing indeterminate biliary strictures: A large sample size retrospective study

BACKGROUND AND AIM

Brush cytology is widely applied to diagnosis indeterminate biliary stricture but suffer from low sensitivity. Changes in DNA content are a character of malignant cell and can be detected by DNA image cytometry (DNA-ICM). The study aimed to estimate the value of routine cytology (RC), DNA-ICM, and their combination in diagnosing indeterminate biliary strictures.

METHODS

A total of 362 patients who underwent both RC and DNA-ICM tests were analysed. Their results were retrospectively applied to final diagnoses. Diagnostic values were compared among RC, DNA-ICM, and their combination based on the location of strictures.

RESULTS

The DNA-ICM and combination of two methods had higher diagnostic accuracy than RC in all strictures (63.3% vs 42.3%, P < 0.001, 64.36% vs 42.3%, P < 0.001) and in distal strictures (65.36% vs 42.81%, P < 0.001, 66.01% vs 42.81%, P < 0.001). But in proximal strictures, DNA-ICM showed no superior (51.8% vs 42.81%, P = 0.184). Combination of two methods was not fully significant superior to RC in proximal strictures (55.36% vs 39.29%, P = 0.089). After classification of "suspicious for malignancy" as positive for malignancy, the diagnostic accuracy of DNA-ICM was still higher than that of RC in all strictures (63.3% vs 51.9%, P = 0.002) and in distal strictures (65.36% vs 52.29%, P = 0.001). Combination of two methods was no superior to DNA-ICM alone (64.36% vs 63.3%, P = 0.757). The utilization of DNA-ICM was more accurate in distal strictures than in proximal strictures (65.36% vs 51.8%, P = 0.017).

CONCLUSION

DNA-ICM is an objective and effective addition tool with RC, especially in distal strictures. The combination of DNA-ICM and RC showed no superior to DNA-ICM alone but could improve diagnostic accuracy to RC in proximal strictures although not fully significant.

Implementation of a real-time reference and calibration grid platform for improved screening - mapping in Pap test slides

Cervical cancer screening based on the Papanicolaou (Pap) test is a widely applied but not always efficient practice for detecting Human Papillomavirus (HPV) mediated lesions, partially due to a non-systematic and inadequate screening process. Our aim was to introduce an inexpensive easy-to-use direct screening platform for improved detection of abnormal cells indicative of underlying cervical neoplasia as well as persisting HPV infection. By employing a novel, efficient technique of laser-based micromachining, we achieved the fabrication of spatial grids on commercially available coverslips allowing visual segmentation of the slide for efficient screening. Abnormal and formerly diagnosed as negative for intraepithelial lesion or malignancy (NILM) Pap test slides (n = 200) were analyzed by conventional and grid-based screening. Grid-based microscopy led to a more reliable diagnosis compared to the conventional by identifying an increased number of abnormal cells (P = 0.001). It decreased borderline ASCUS, AGC diagnosis, increasing LSIL, HSIL and in situ AdenoCa detection rates closely related with biopsy (P = 0.015; kappa = 0.978). Concerning the set of NILM diagnoses in rapid re-screening, the method upgraded six cases (n = 6) to LSIL (P = 0.001). The proposed technical solution offers a calibration and orientation visual aid during the on-site screening process providing significant advantages compared to expensive digital imaging techniques.

mRNA expression of CDH3, IGF2BP3, and BIRC5 in biliary brush cytology specimens is a useful adjunctive tool of cytology for the diagnosis of malignant biliary stricture

Although advances have been made in diagnostic tools, the distinction between malignant and benign biliary strictures still remains challenging. Intraductal brush cytology is a convenient and safe method that is used for the diagnosis of biliary stricture, but, low sensitivity limits its usefulness. This study aimed to demonstrate the usefulness of mRNA expression levels of target genes in brush cytology specimens combined with cytology for the diagnosis of malignant biliary stricture. Immunohistochemistry for cadherin 3 (CDH3), p53, insulin-like growth factor II mRNA-binding protein 3 (IGF2BP3), homeobox B7 (HOXB7), and baculoviral inhibitor of apoptosis repeat containing 5 (BIRC5) was performed in 4 benign and 4 malignant bile duct tissues. Through endoscopic or interventional radiologic procedures, brush cytology specimens were prospectively obtained in 21 and 35 paitents with biliary strictures. In the brush cytology specimens, the mRNA expressions levels of 5 genes were determined by real-time polymerase chain reaction. Immunohistochemistry for CDH3, p53, IGF2BP3, HOXB7, and BIRC5 all showed positive staining in malignant tissues in contrast to benign tissues, which were negative. In the brush cytology specimens, the mRNA expression levels of CDH3, IGF2BP3, HOXB7, and BIRC5 were significantly higher in cases of malignant biliary stricture compared with cases of benign stricture (P = 0.006, P < 0.001, P < 0.001, and P = 0.001). The receiver-operating characteristic curves of these 4 mRNAs demonstrated that mRNA expression levels are useful for the prediction of malignant biliary stricture (P = 0.006, P < 0.001, P < 0.001, and P = 0.002). The sensitivity and specificity, respectively, for malignant biliary stricture were 57.1% and 100% for cytology, 57.1% and 64.3% for CDH3, 76.2% and 100% for IGF2BP3, 71.4% and 57.1% for HOXB7, and 76.2% and 64.3% for BIRC5. When cytology was combined with the mRNA levels of CDH3, IGF2BP3, or BIRC5, the sensitivity for malignant biliary stricture improved to 90.5%. The measurement of the mRNA expression levels of CDH3, IGF2BP3, and BIRC5 by real-time polymerase chain reaction combined with cytology was useful for the differentiation of malignant and benign biliary strictures in brush cytology specimens.

Whole slide image with image analysis of atypical bile duct brushing: Quantitative features predictive of malignancy

Background:

Whole slide images (WSIs) involve digitally capturing glass slides for microscopic computer-based viewing and these are amenable to quantitative image analysis. Bile duct (BD) brushing can show morphologic features that are categorized as indeterminate for malignancy. The study aims to evaluate quantitative morphologic features of atypical categories of BD brushing by WSI analysis for the identification of criteria predictive of malignancy.

Materials and Methods:

Over a 3-year period, BD brush specimens with indeterminate diagnostic categorization (atypical to suspicious) were subjected to WSI analysis. Ten well-visualized groups with morphologic atypical features were selected per case and had the quantitative analysis performed for group area, individual nuclear area, the number of nuclei per group, N: C ratio and nuclear size differential.

Results:

There were 28 cases identified with 17 atypical and 11 suspicious. The average nuclear area was 63.7 µm² for atypical and 80.1 µm² for suspicious (+difference 16.4 µm²; P = 0.002). The nuclear size differential was 69.7 µm² for atypical and 88.4 µm² for suspicious (+difference 18.8 µm²; P = 0.009). An average nuclear area >70 µm² had a 3.2 risk ratio for suspicious categorization.

Conclusion:

The quantitative criteria findings as measured by image analysis on WSI showed that cases categorized as suspicious had more nuclear size pleomorphism (+18.8 µm²) and larger nuclei (+16.4 µm²) than those categorized as atypical. WSI with morphologic image analysis can demonstrate quantitative statistically significant differences between atypical and suspicious BD brushings and provide objective criteria that support the diagnosis of carcinoma.