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

Updated techniques and evidence for endoscopic ultrasound-guided tissue acquisition from solid pancreatic lesions

Endoscopic ultrasound-guided tissue acquisition (EUS-TA), including fine-needle aspiration (EUS-FNA) and fine-needle biopsy (EUS-FNB), has revolutionized specimen collection from intra-abdominal organs, especially the pancreas. Advances in personalized medicine and more precise treatment have increased demands to collect specimens with higher cell counts, while preserving tissue structure, leading to the development of EUS-FNB needles. EUS-FNB has generally replaced EUS-FNA as the procedure of choice for EUS-TA of pancreatic cancer. Various techniques have been tested for their ability to enhance the diagnostic performance of EUS-TA, including multiple methods of sampling at the time of puncture, on-site specimen evaluation, and specimen processing. In addition, advances in next-generation sequencing have made comprehensive genomic profiling of EUS-TA samples feasible in routine clinical practice. The present review describes updates in EUS-TA sampling techniques of pancreatic lesions, as well as methods for their evaluation.

Advances in diagnostic liquid-based cytology

Liquid-based cytology (LBC) has changed the landscape of gynaecological cytology. A growing demand exists for LBC in diagnostic cytology, particularly for ancillary testing, such as immunocytochemistry and molecular testing. Ancillary testing solely based on conventional preparation (CP) methods remains challenging. Recently, the increased demand for specialist testing and minimally invasive techniques, such as endoscopic ultrasonography fine-needle aspiration, to obtain cellular samples has led to an increasing demand for ancillary testing on cytology LBC supernatant, slides and cell block (CB). This facilitates the diagnosis and prognosis in cytology samples enabling personalized treatment. An understanding of the history and future prospects of LBC is crucial for its application in routine diagnostics by cytopathologists and cytotechnologists. In this review, we initiated an internet search using the keyword 'liquid-based cytology', and we conducted a literature review to discuss the usefulness of combined diagnosis of LBC and CP, immunocytochemistry and molecular testing and assessed the quality of nucleic acids in diagnostic LBC. High-quality and cell-rich diagnostic LBC surpassed the CP method alone in terms of reliability and versatility of ancillary testing in cytological diagnosis. Conclusively, diagnostic LBC lends itself to various new technologies and is expected to continue evolving with innovations in the future.

Tissue processing of endoscopic ultrasound-guided fine-needle aspiration specimens from solid pancreatic lesions

Now that tissue cores can be obtained using fine-needle biopsy (FNB) needles, the ways tissues are handled for endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) are changing. Direct smear, touch smear of core tissues, and centrifugation have been used for cytological examinations, and liquid-based cytology (LBC), which allows immunostaining and genetic tests that use residual samples, is emerging as an alternative. We emphasize that liquid cytology (Cytospin™ cytology and LBC) is still important, because it enables the diagnosis of pancreatic ductal adenocarcinoma (PDAC) when cancerous cells are scarce in specimens. Cell blocks are being replaced by core tissues obtained via FNB needles. Recent reports indicate that rapid on-site evaluation (ROSE) is not necessary when FNB needles are used, and macroscopic on-site evaluation is used to evaluate specimen adequacy. Macroscopic findings of specimens are helpful in the diagnostic workup and for clarifying specimen-handling methods. In addition to the red strings and white cores observed in PDAC, mixed red and white strings, gray tissues, and gelatinous tissues are observed. Gray (necrotic) tissues and gelatinous (mucus) tissues are more suitable than histology for cell block or cytological processing. Tumor cells in neuroendocrine tumors (NETs) are numerous in red strings but cannot be observed macroscopically. ROSE might thus be necessary for lesions that may be NETs. Core tissues can be used for genetic tests, such as those used for KRAS mutations and comprehensive genomic profiling. Cytological materials, including slides and LBC specimens, can also be genetic test materials.

Factors affecting the diagnostic value of liquid-based cytology by EUS-FNA in the diagnosis of pancreatic cystic neoplasms

Background and Objectives

This study retrospectively evaluated the value of liquid-based cytology (LBC) alone for diagnosing pancreatic cystic neoplasms (PCNs) in a large sample and initially estimated factors that might affect LBC diagnostic ability.

Methods

From April 2015 to October 2022, we prospectively enrolled 331 patients with suspected PCNs in our prospective database. Among them, 112 patients chosen to receive surgical resection were included. Only 96 patients who underwent EUS-guided cystic fluid LBC were finally studied. The diagnostic values of LBC for differentiating benign and malignant PCNs and subtypes of PCNs were evaluated.

Results

There were 71 female and 25 male patients with a mean age of 47.6 ± 14.4 years. The median cyst size was 43.4 mm. The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of LBC for the differentiation of benign and malignant PCNs were 96.9%, 57.1%, 100%, 100%, and 96.7%, respectively. The overall diagnostic accuracy of LBC for specific cyst types was 33.3% (32/96). Cysts located in the pancreatic body/tail or with irregular shapes were more likely to obtain a definite LBC diagnosis. At the same time, age, sex, tumor size, cystic fluid viscosity, operation time, needle type, and presence of septation were not significantly different.

Conclusion

Liquid-based cytology alone is useful for differentiating benign PCNs from malignant PCNs and can successfully characterize the PCN subtypes in one-third of patients. Pancreatic cystic neoplasms located in the body/tail or exhibiting irregular shapes are more likely to obtain a definite LBC diagnosis.

Echoendoscopic ultrasound pancreatic adenocarcinoma diagnosis and theranostic approach: should KRAS mutation research be recommended in everyday practice?

Background

The impact of KRAS mutation testing on pancreatic ductal adenocarcinoma (PDAC) samples by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for reducing the need to repeat EUS-FNA has been demonstrated. Such testing however is not part of standard practice for endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB).

Objectives

We aim to analyse the proportion of non-contributive samples by EUS-FNB and to evaluate the impact of KRAS mutation testing on the diagnosis, theranostics and survival.

Design

In this retrospective study, the impact on diagnosis and survival of KRAS testing for contributive and non-contributive samples by EUS-FNB was analysed.

Methods

The EUS-FNB samples, combined with KRAS testing using the Idylla® technique on liquid-based cytology from patients with PDAC between February 2019 and May 2023, were retrospectively reviewed. The cytology results were classified according to the guidelines of the World Health Organization System for Reporting Pancreaticobiliary Cytopathology (WHOSRPC).

Results

A total of 85 EUS-FNB specimens were reviewed. In all, 25 EUS-FNB samples did not lead to a formal diagnosis of PDAC according to the WHOSRPC (30.2%). Out of these 25, 11 (44%) could have been considered positive for a PDAC diagnosis thanks to the KRAS mutation test without carrying out further diagnosis procedures. The sensitivity of KRAS mutation testing using the Idylla technique was 98.6%. According to the available data, survival rates were not statistically different depending on the type of mutation.

Conclusion

KRAS mutation testing on liquid-based cytology using the Idylla or equivalent technique, combined with the PDAC EUS-FNB sample, should become a standard for diagnosis to avoid delaying treatment by doing another biopsy. Furthermore, knowledge of the KRAS status from treatment initiation could be used to isolate mutations requiring targeted treatments or inclusion in clinical research trials, especially for wild-type KRAS PDAC.

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.

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.