Assessment of Risk of Malignancy by Application of the Proposed IAC-IARC-WHO Cytopathology System for Classification and Reporting of Soft Tissue Lesions: An Experience From Tertiary Care Center From India.

Introduction: Soft tissue lesions encompass a diverse category of diseases from benign to malignant, and their morphology might overlap; therefore, accurate categorization is needed to approach the reporting of soft tissue cytology. The cytology of these lesions is helpful in detecting the features of malignancy, which helps in guiding further management. In this study, we applied the proposed IAC-IARC-WHO cytopathology system to assess the risk of malignancy (ROM) and diagnostic accuracy (DA) for the determination of its clinical and diagnostic utility.

Methods And Materials: This was a 5-year retrospective study of fine needle aspirations (FNA) of soft tissue, which were categorized according to the proposed IAC-IARC-WHO system. Cytological diagnoses were correlated with the corresponding histopathological diagnoses to assess diagnostic accuracy and ROM for each diagnostic category and to evaluate the diagnostic utility of FNAC by analyzing the sensitivity, specificity, and accuracy.

Results: A total of 1509 FNAC cases of soft tissue lesions were classified under the proposed six categories of the IAC-IARC-WHO system. Final histology was compared with cytology in 250 cases. Considering malignant diagnosis as a positive result, the overall sensitivity, specificity, and accuracy of FNAC were found to be 58.14%, 99.03%, and 92%, respectively. ROM was calculated in each category, which had a wide range from 7.6% to 100%.

Conclusion: We have validated the IAC-IARC-WHO system for soft tissue cytology and found it to be effective with the sensitivity and specificity results. FNA categorization is helpful for better communication between cytopathologists and clinicians, ensuring better reproducibility, which is crucial for guiding further diagnostic workup and surgical management.