Diagnostic Efficacy of Liquid-Based Cytology in Endoscopic Ultrasound-Guided Fine Needle Aspiration for Pancreatic Mass Lesions During the Learning Curve: A Retrospective Study

Role of Liquid-Based Cytology in the Endoscopic Diagnosis of Pancreatic Ductal Adenocarcinoma

Recently, endoscopic ultrasound-guided tissue acquisition (EUS-TA) has been widely used to diagnose pancreatic ductal adenocarcinoma (PDAC). The histological examination of core tissues acquired using novel biopsy needles is the primary diagnostic approach for patients with PDAC. However, in patients with early-stage PDAC, such as Stages 0 and I, EUS-TA can be challenging, and its diagnostic accuracy may be limited. This presents a clinical dilemma: The earlier that clinicians attempt to accurately diagnose PDAC, the more difficult it becomes to do so using EUS-TA. Liquid-based cytology (LBC) is a technique for preparing pathological specimens from liquefied cytology specimens by placing the collected material in a special fixative preservative fluid. LBC offers advantages, such as specimen optimization with reduced blood interference, a high cell-collection rate, and the simplicity of the procedure in the endoscopy room. The use of LBC may improve diagnostic accuracy, particularly for early-stage PDAC. Therefore, we emphasize that cytology remains a valuable tool for the endoscopic diagnosis of PDAC. In this review, we discuss the role of LBC in the endoscopic diagnosis of PDAC.

Diagnostic yield of liquid-based cytology in serial pancreatic juice aspiration cytological examination

OBJECTIVES

Serial pancreatic juice aspiration cytological examination (SPACE) via endoscopic retrograde cholangiopancreatography is a useful diagnostic method for early-stage pancreatic cancer, such as carcinoma in situ that are difficult to diagnose by endoscopic ultrasound-guided fine needle aspiration (EUS-FNA). However, the diagnostic accuracy of SPACE is low, which is attributed to problems regarding specimen treatment. Hence, we evaluated the diagnostic efficacy of liquid-based cytology (LBC) in pancreatic juice cytology for pancreatic cancer.

METHODS

We retrospectively analyzed 24 patients with suspected pancreatic cancer that was difficult to diagnose by endoscopic ultrasound-guided fine needle aspiration who underwent SPACE using LBC between April 2017 and April 2021.

RESULTS

The most common reason for performing SPACE was localized stenosis of the main pancreatic duct without a mass. Eleven patients were diagnosed with malignancy after surgical resection, nine of whom had pancreatic ductal adenocarcinoma. Ten patients were diagnosed as benign after a follow-up of more than 1 year. The nine cases of malignancy were diagnosed before surgical resection by SPACE using LBC, with a sensitivity of 81.8% and specificity of 100%. The overall diagnostic accuracy was 91.7%. A total of 152 LBC examinations were performed via SPACE, with an adequate sample collection rate of 88.9%. No adverse events, including acute pancreatitis, occurred after endoscopic retrograde cholangiopancreatography.

CONCLUSION

SPACE with LBC offers good diagnostic efficacy in patients with pancreatic cancer that is difficult to diagnose by endoscopic ultrasound-guided fine needle aspiration.

The usefulness of liquid-based cytology for endoscopic ultrasound-guided tissue acquisition of solid pancreatic masses

Liquid-based cytology (LBC) is used primarily for cervical cytology, although it is also used for analyzing liquid samples such as urine and ascites specimens, as well as fine needle aspiration material, such as those obtained from breast and thyroid. The usefulness of the LBC method for endoscopic ultrasound-guided tissue acquisition (EUS-TA) of solid pancreatic masses was recently reported. The LBC method can produce multiple pathological slides and can be applied to immunocytochemistry and genetic analyses. In this article, we review the usefulness of LBC for EUS-TA of solid pancreatic masses.

Evaluation and diagnostic value of next-generation sequencing analysis of residual liquid-based cytology specimens of pancreatic masses

BACKGROUND

Liquid-based cytology (LBC) is a widely used method for processing specimens obtained by endoscopic biopsy. This study evaluated next-generation sequencing (NGS) analysis of LBC specimens to improve the diagnostic accuracy of pancreatic lesions.

METHODS

Upon the diagnosis of a suspected pancreatic mass, LBC residues were used retrospectively. The quantity and quality of DNA extracted from residual LBC samples were evaluated, and an NGS analysis targeting 6 genes (KRAS, GNAS, TP53, CDKN2A, SMAD4, and PIK3CA) was performed.

RESULTS

The library was prepared from LBC specimens taken from 52 cases: 44 were successful, and 8 preparations failed. An analysis of DNA quantity and quality suggested that the success or failure of NGS implementation depended on both properties. The final diagnosis was achieved by a combination of the pathological analysis of the surgical excision or biopsy material with clinical information. Among the 33 cases of pancreatic ductal adenocarcinoma (PDAC), KRAS, TP53, CDKN2A, and SMAD4 mutations were identified in 31 (94%), 16 (48%), 3 (9%), and 2 (6%), respectively. Among the 11 benign cases, only a KRAS mutation was identified in 1 case. On the basis of NGS results, 18 of 33 PDACs (55%) were classified as highly dysplastic or more, and 10 of 11 benign lesions were evaluated as nonmalignant, which was consistent with the final diagnosis.

CONCLUSIONS

NGS analysis using LBC specimens from which DNA of appropriate quantity and quality has been extracted could contribute to improving the assessment of pancreatic tumor malignancies and the application of molecular-targeted drugs.

Impact of LBC fixative type and fixation time on molecular analysis of pancreatic cancer cells: A comparative study of cell morphology, antigenicity and nucleic acids

Introduction:

Liquid-based cytology (LBC) has been widely used since 2000. Next-Generation Sequencing (NGS) analysis of residual specimens in LBC fixative may also be performed for pancreatic cancer in the near future. We examined cell morphology, antigenicity and nucleic acids in pancreatic cancer cells at different fixation times using two types of LBC fixatives.

Methods:

PANC-1 cells were fixed in 1 ml CytoRich Red (CR), CytoRich Blue (CB), 95% ethanol (95% AL) or 10% neutral buffered formalin (10% NBF) and evaluated for cell area, antigenicity and nucleic acids with fixation times of 1 hour and 1, 3, 9, and 14 days. Antigenicity was evaluated by immunocytochemical staining for p53 and CK20, and nucleic acid fragmentation was assessed by real-time PCR.

Results:

There was no difference in total cell area between 1 hour and 14 day fixation times for the CR group, but the CB group showed cell contraction with 9 days fixation. In immunocytochemical staining, the CR group showed high p53 and CK20 positivity even after 14 days fixation. The CB group had a lower p53 positive rate than the CR group from 1 hour fixation. For nucleic acid fragmentation, Ct values for the CR group increased with fixation time. The CB group had consistently low Ct values.

Conclusion:

Different LBC fixatives and fixation time can have varying effects on cell morphology, antigenicity and nucleic acids in pancreatic cancer cells. Therefore, fixative type and fixation time should be considered for molecular testing on residual samples in LBC fixatives.

Value of contrast-enhanced ultrasound combined with percutaneous ultrasound-guided fine-needle aspiration in the diagnosis of solid pancreatic lesions

Background:

Contrast-enhanced ultrasound (CEUS) can detect lesions hidden in inflammatory regions and find necrosis or areas of severe fibrosis within the lesion. This retrospective study aimed to compare the diagnostic accuracy of solid pancreatic lesions using percutaneous ultrasound (US)-guided fine-needle aspiration (FNA) with or without CEUS assessment.

Methods:

Clinical, imaging, and pathologic data of 181 patients from January 2014 to December 2018 in Pecking Union Medical College Hospital, with solid pancreatic masses who underwent percutaneous US-FNA and ThinPrep cytologic test were retrospectively evaluated. Patients were divided into CEUS and US groups according to whether CEUS was performed before the biopsy. According to FNA cytology diagnoses, we combined non-diagnostic, neoplastic, and negative cases into a negative category. The positive category included malignant, suspicious, and atypical cases. The final diagnosis was confirmed by pathology or clinical and radiological follow-up for at least 12 months. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of US-FNA were evaluated between the two groups.

Results:

This study enrolled 107 male and 74 female patients (average age: 60 years). There were 58 cases in the US group and 123 cases in the CEUS group. No statistically significant differences in age, gender, or lesion size were found between the two groups. The diagnostic accuracy of the CEUS group was 95.1% (117/123), which was higher than the 86.2% (50/58) observed in the US group (P = 0.036). The sensitivity, specificity, PPV, and NPV of the CEUS group were increased by 7.5%, 16.7%, 3.4%, and 18.8%, respectively, compared with the US group. However, the differences of the two groups were not statistically significant.

Conclusions:

Compared with the conventional US, the use of CEUS could improve the biopsy accuracy and avoid the need for a repeat biopsy, especially for some complicated FNA cases.

Comparison of EUS-guided conventional smear and liquid-based cytology in pancreatic lesions: A systematic review and meta-analysis

Background and study aims  Endoscopic ultrasound (EUS)-guided fine-needle aspiration (EUS-FNA) has limitations of inadequate sampling and false-negative results for malignancy. It has been performed using conventional smear (CS) cytology with rapid on-site evaluation (ROSE) with reasonable diagnostic accuracy. An alternative to ROSE is liquid-based cytology (LBC). Commonly used LBC techniques include precipitation-based (SurePath™) and filtration-based (ThinPrep ^® , CellPrep ^® ). Data regarding the diagnostic efficacy of LBC compared with CS are limited. Methods  Multiple databases were searched through March 2020 to identify studies reporting diagnostic yield of EUS-guided CS and LBC in pancreatic lesions. Pooled diagnostic odds and rates of performance for the cytologic diagnoses of benign, suspicious, and malignant lesions were calculated. Diagnostic efficacy was evaluated by pooled rates of accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). Results  Nine studies with a total of 1308 patients were included in our final analysis. Pooled diagnostic odds of CS cytology were 1.69 (CI 1.02-2.79) and 0.39 (CI 0.19-0.8) for malignant lesions when compared to filtration-based and precipitation-based LBC techniques, respectively. For CS, precipitation-based and filtration-based LBC, pooled diagnostic accuracy was 79.7 %, 85.2 %, 77.3 %, sensitivity was 79.2 %, 83.6 %, 68.3 %, and specificity was 99.4 %, 99.5 %, 99.5 %, respectively. Conclusions  The precipitation-based LBC technique (SurePath™) had superior diagnostic odds for malignant pancreatic lesions compared with CS cytology in the absence of ROSE. It showed superior accuracy and sensitivity, but comparable specificity and PPV. Diagnostic odds of CS cytology in the absence of ROSE were superior to the filtration-based LBC technique (ThinPrep ^® , Cellprep ^® ) for diagnosing malignant pancreatic lesions.

Pathologic interpretation of endoscopic ultrasound-guided fine needle aspiration cytology/biopsy for pancreatic lesions

Pathologic interpretation of endoscopic ultrasound–guided fine needle aspiration (EUS-FNA) cytology/biopsy specimens is one of the most challenging tasks in cytology and surgical pathology practice, as the procedure often yields minimal amounts of diagnostic material and contains contaminants, such as blood cells and normal intestinal mucosa. EUS-FNA cytology/biopsy will nevertheless become a more popular procedure for evaluation of various pancreatic lesions because they are difficult to approach with conventional endoscopic procedures. Pathologists should understand the structural differences and limitations of EUS-FNA that make pathologic diagnosis difficult. Ancillary tests are available for differential diagnosis of EUS-FNA for various pancreatic lesions. Immunostains are the most commonly used ancillary tests, and pathologists should able to choose the necessary panel for differential diagnosis. Pathologists should review clinical history and radiologic and/or EUS findings before selecting an immunostain panel and making a pathologic diagnosis. In addition, one’s threshold of malignancy should be adjusted according to the appropriate clinical setting to avoid under-evaluation of pathologic diagnoses. Clinico-pathologic correlation is essential in pathologic evaluation of EUS-FNA for pancreatic lesions. Pathologists can reduce errors by correlating clinical and radiologic findings when evaluating EUS-FNA. Some molecular tests can be applied in differential diagnosis of pancreatic neoplastic and cystic lesions. Molecular data should be used as supportive evidence of a specific disease entity, rather than direct evidence, and should be correlated with clinico-pathologic findings to avoid errors in pathologic diagnosis.