The_World_Health_Organization_Reporting_System_for_Pancreaticobiliary cytology

WHO Reporting System for Pancreaticobiliary Cytopathology

  • Overview

    • Presented by the WHO, the International Academy of Cytology, and the International Agency for Research on Cancer.

    • Standardized reporting system aimed at pancreaticobiliary cytopathology.

    • Introduces a 7-tiered classification system:

      • 1. Insufficient/Inadequate/Nondiagnostic

      • 2. Benign (Negative for Malignancy)

      • 3. Atypical

      • 4. Pancreatic Neoplasm of Low Risk/Low Grade

      • 5. Pancreatic Neoplasm of High Risk/High Grade

      • 6. Suspicious for Malignancy

      • 7. Malignant

Key Differences Compared to PSC System

  • PSC system had a 6-tiered system with:

    • A single 'neoplastic' lesion category.

    • Benign neoplastic tumors (primarily serous cystadenoma) and other neoplasms were combined, complicating risk estimates.

  • In the WHO system:

    • Distinction between benign neoplasms (almost no risk of malignancy) and low-grade malignant tumors.

    • Focus on non-invasive premalignant lesions and their stratification by cytomorphological grades.

Estimated Risk of Malignancy (ROM) by Diagnostic Category

Category

Estimated ROM (%)

Management Options

Insufficient/Inadequate/Nondiagnostic

5–25

Repeat FNAB

Benign (Negative for Malignancy)

0–15

Clinical correlation

Atypical

30–40

Repeat FNAB

Pancreatic Neoplasm of Low Risk/Low Grade

5–20

Clinical correlation

Pancreatic Neoplasm of High Risk/High Grade

60–95

Surgical resection or conservative management

Suspicious for Malignancy

80–100

Treat as positive if surgically managed

Malignant

99–100

Based on clinical stage

Category Definitions

1. Insufficient/Inadequate/Nondiagnostic

  • Definition: Specimens that can’t provide a diagnosis due to insufficient or non-diagnostic quality.

  • Discussion: Achieving adequate samples is pivotal; factors like operator experience and sampling technique significantly affect outcomes.

2. Benign (Negative for Malignancy)

  • Definition: No evidence of malignancy or cellular atypia.

  • Discussion: Includes conditions like pancreatitis and pseudocysts. Cells present in adequate quantity, but no malignancy is observed.

3. Atypical

  • Definition: Features suggestive of benign lesions but not enough to classify conclusively.

  • Discussion: Represents a range of findings from benign to malignant potentials; clinical context is important for diagnostic decisions.

4. Pancreatic Neoplasm of Low Risk/Low Grade (PaN-Low)

  • Definition: Low-grade epithelial atypia present in intraductal or cystic neoplasms.

  • Discussion: Requires careful correlation with cyst fluid analysis and clinical features for management.

5. Pancreatic Neoplasm of High Risk/High Grade (PaN-High)

  • Definition: High-grade epithelial atypia found in neoplasms.

  • Discussion: Highly predictive of high-grade dysplasia/carcinoma; affects treatment options closely tied to patient health status.

6. Suspicious for Malignancy

  • Definition: Demonstrates characteristics that raise concern for malignancy without definitive diagnosis.

  • Discussion: Management strategies should align clinical findings, with caution in using this category due to potential overlap with benign findings.

7. Malignant

  • Definition: Clear cytopathological features indicative of malignancy.

  • Discussion: Encompasses a variety of tumor types; surgical management is typically the first course of action.

Conclusion

  • The new WHO Reporting System aims to enhance communication and clarity in cytopathology practice, improving patient management workflows. END.