Risk of Malignancy Using the Diagnostic Categories Proposed by the World Health Organization International System for Reporting Pancreaticobiliary Cytopathology

Reproducibility assessment of WHO reporting system for pancreaticobiliary cytopathology: A single institution experience

BACKGROUND

The World Health Organization (WHO) reporting system for pancreaticobiliary cytopathology was released to internationalize the reporting, assisting in correct diagnosis and patient treatment with significant revisions from the previous Papanicolaou Society of Cytopathology (PSC) system. The "neoplastic: benign" and "neoplastic: other" categories have mostly been superseded by two new ones: "pancreatic neoplasia-low-grade" (PaN-low) and "pancreatic neoplasia-high-grade" (PaN-high), which classify intermediate neoplastic lesions based on cytological atypia. We aim to assess the reproducibility and risk of malignancy (ROM) for reporting pancreaticobiliary cytopathology by the WHO system in comparison with the PSC system.

MATERIALS AND METHODS

A retrospective study by reviewing archival slides sent for pancreaticobiliary cytological evaluation from June 2021 to June 2023, by two pathologists blinded to each other's findings. Absolute ROM was determined by histopathology/cell block study/clinical follow-up (minimum 6 months)/overtly malignant imaging/metastasis.

RESULTS

A total of 332 cases from 329 patients met the inclusion criteria, comprising pancreatic, gallbladder, and biliary lesions. The median patient age was 54 years (range, 14-86 years). The overall sensitivity of the test is 74.9% specificity is 93.2%, positive predictive value of 96.8%, negative predictive value of 57.6%, and a diagnostic accuracy of 81.8%. The absolute ROM for each site in all categories was comparable with that of the published data from the WHO system.

CONCLUSION

Our study highlights the reliability of the WHO system for guiding clinical decision-making and patient management in the context of pancreaticobiliary. However, continual efforts among pathologists are essential to maintain consistent accuracy in cytological interpretations.

Pancreaticobiliary Cytology Practice in 2021: Results of a College of American Pathologists Survey

CONTEXT.—

The College of American Pathologists (CAP) surveys provide national benchmarks of pathology practice.

OBJECTIVE.—

To investigate pancreaticobiliary cytology practice in domestic and international laboratories in 2021.

DESIGN.—

We analyzed data from the CAP Pancreaticobiliary Cytology Practice Supplemental Questionnaire that was distributed to laboratories participating in the 2021 CAP Nongynecologic Cytopathology Education Program.

RESULTS.—

Ninety-three percent (567 of 612) of respondent laboratories routinely evaluated pancreaticobiliary cytology specimens. Biliary brushing (85%) was the most common pancreaticobiliary cytology specimen evaluated, followed by pancreatic fine-needle aspiration (79%). The most used sampling methods reported by 235 laboratories were 22-gauge needle for fine-needle aspiration (62%) and SharkCore needle for fine-needle biopsy (27%). Cell block was the most used slide preparation method (76%), followed by liquid-based cytology (59%) for pancreatic cystic lesions. Up to 95% (303 of 320) of laboratories performed rapid on-site evaluation (ROSE) on pancreatic solid lesions, while 56% (180 of 320) performed ROSE for cystic lesions. Thirty-six percent (193 of 530) of laboratories used the Papanicolaou Society of Cytopathology System for Reporting Pancreaticobiliary Cytology in 2021. Among all institution types, significant differences in specimen volume, specimen type, ROSE practice, and case sign-out were identified. Additionally, significant differences in specimen type, slide preparation, and ROSE practice were found.

CONCLUSIONS.—

This is the first survey from the CAP to investigate pancreaticobiliary cytology practice. The findings reveal significant differences among institution types and between domestic and international laboratories. These data provide a baseline for future studies in a variety of practice settings.

The WHO system versus the Papanicolaou society of cytopathology system for reporting pancreaticobiliary cytology for risk stratification-which is better?

BACKGROUND

Recently, the World Health Organization (WHO) has proposed a reporting system for pancreaticobiliary cytopathology. We applied this classification for pancreatic lesion samples by fine needle aspiration (FNA) and compared the results to the previous classification of the Papanicolaou Society of Cytopathology (PSC) system for risk stratification.

METHODS

The computerized database was searched for all pancreatic endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) and transabdominal ultrasound-guided FNA (TUS-FNA) samples from 2016 to 2020 and cases were reassigned as per the PSC and the WHO diagnostic categories. Cases with follow-up, clinicoradiological, and/or histopathology were included in the study. The risk of malignancy (ROM) was calculated across all diagnostic categories based on clinical data, imaging data, and histopathology wherever available.

RESULTS

There were a total of 625 pancreatic FNA. In 230 cases, follow-up information was available which included 116 EUS and 114 TUS-FNA samples. The ROM for PSC categories I-VI was 40%, 19.7%, 28.6%, 57.1%, 94.7%, and 97.9% and for the WHO categories (I-VII), it was 60%, 21.3%, and 35.7%, not representative, not applicable, 94.7% and 94.9%. The overall sensitivity and specificity of PSC was 68.2% and 96.2% when categories V and VI were taken as positive and 78.9% and 93.3% for WHO when categories VI and VII were taken as positive.

CONCLUSIONS

Pancreatic FNA samples reported as per the WHO system showed better sensitivity as compared to the PSC system resulting in better risk stratification and consequently better patient management. The overall high specificity and moderate sensitivity reaffirm the utility of FNA in pancreatic lesions.

The World Health Organization classification of pancreaticobiliary cytopathology stratifies risk of malignancy and outcome for endoscopic ultrasound-guided fine-needle aspiration of the pancreas

BACKGROUND

The World Health Organization (WHO) has recently published a classification for reporting pancreaticobiliary cytopathology with differences compared to the Papanicolaou Society of Cytopathology (PSC) classification.

METHODS

Retrospective data were collected from pancreatic endoscopic ultrasound-guided fine-needle aspirations from 2014 to 2017 at a pancreatic cancer center. Absolute risk of malignancy (AROM), relative risk (to benign), performance characteristics, and overall survival were calculated for the entire cohort with comparison of cysts and solid lesions.

RESULTS

In total, 2562 cases were included: 16% cyst (n = 411) and 84% solid (n = 2151). The histologic confirmation rate was 43% (n = 1101) and the median follow-up (for benign) was 56 months. For WHO I-VII, overall AROM (%) was 23, 22, 62, 13, 65, 97, and 100; cyst AROM was 7, 0, 19, 13, 38, 78, and 100; and solid AROM was 50, 29, 70, 15, 100, 99, and 100. For PSC I-VI, overall AROM (%) was 23, 29, 64, 0 (IVa), 60 (IVb), 97, and 100; cyst AROM was 7, 0, 19, 0, 21, 78, and 100; and solid AROM was 50, 35, 73, 0, 92, 99, and 100. The difference in relative risk for a cyst (vs. solid) overall was 0.38 for WHO and 0.26 for PSC. WHO and PSC categories showed stratification for the probability of overall survival.

CONCLUSIONS

Cystic versus solid lesion type can dramatically affect AROM, particularly for nondiagnostic (I), benign (II), atypical (III), and WHO V categories. WHO IV conveys a similarly low AROM for cystic and solid types. Both classifications stratify the probability of overall survival, including the newly introduced categories WHO IV and WHO V.

Risk Factors and Interpretation of Inconclusive Endoscopic Ultrasound-Guided Fine Needle Aspiration Cytology in the Diagnosis of Solid Pancreatic Lesions

BACKGROUND

The inconclusive cytological findings of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) remain a major clinical challenge and often lead to treatment delays.

METHODS

Patients who had undergone EUS-FNA sampling for solid pancreas lesions between 2014 and 2021 were retrospectively enrolled. The "atypical" and "non-diagnostic" categories of the Papanicolaou Society of Cytopathology System were considered inconclusive and the "negative for malignancy" category of malignancy was suspected clinically. We determined the frequency and predictors of inconclusive cytological finding.

RESULTS

A total of 473 first EUS-FNA samples were included, of which 108 cases (22.83%) were inconclusive. Significant increases in the odds of inconclusive cytological findings were observed for lesions with a benign final diagnosis (OR 11.20; 95% CI 6.56-19.54, p < 0.001) as well as with the use of 25 G FNA needles (OR 2.12; 95% CI 1.09-4.01, p = 0.023) compared to 22 G needles. Furthermore, the use of a single EUS-FNA technique compared to the combined use of slow-pull and standard suction techniques (OR 1.70; 95% CI 1.06-2.70, p = 0.027) and less than three punctures per procedure led to an elevation in the risk of inconclusive cytology (OR 2.49; 95% CI 1.49-4.14, p < 0.001). Risk reduction in inconclusive cytology findings was observed in lesions between 2-4 cm (OR 0.40; 95% CI 0.23-0.68, p = 0.001) and >4 cm (OR 0.16; 95% CI 0.08-0.31, p < 0.001) compared to lesions ≤2 cm.

CONCLUSIONS

The more than two punctures per EUS-FNA sampling with larger-diameter needle (19 G or 22 G) using the slow-pull and standard suction techniques in combination may decrease the probability of inconclusive cytological findings.