Fine-Needle Aspiration Cytology of Hepatic Masses: A Retrospective Observational Study and Assessment of Risk of Malignancy Based on the Proposed World Health Organization Reporting System for Liver Cytology.

BACKGROUND: Hepatic masses present a diagnostic challenge due to their variable etiology and overlapping imaging features. While radiology plays a pivotal role in lesion detection and characterization, fine-needle aspiration cytology (FNAC) is a rapid and minimally invasive method. This study reclassifies liver FNAC cases using the World Health Organization (WHO) Reporting System for Liver Cytology and assesses the diagnostic performance and risk of malignancy (ROM) for each category. MATERIALS AND METHODS: This retrospective study analyzed 1741 ultrasound-guided fine-needle aspirations performed on hepatic lesions over 8 years at a tertiary care center. Cytological specimens were reclassified into WHO categories: nondiagnostic, benign, atypical, suspicious for malignancy, and malignant. Histopathology follow-up served as the reference standard. Diagnostic metrics, including sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy, were calculated. ROM was determined for each cytological category. RESULTS: Of the 1741 FNAC cases, 1660 yielded adequate material. Malignant lesions constituted the majority (n = 1254; 72.0%), with metastatic adenocarcinoma being most prevalent. The sensitivity and specificity of FNAC for detecting malignancy were 98.46% and 92.64%, respectively, with a diagnostic accuracy of 97.04%. The ROM for WHO categories ranged from 4.9% in the benign group to 100% in the malignant group. CONCLUSION: FNAC, particularly when classified according to the WHO system, demonstrates high diagnostic accuracy and predictive reliability for hepatic space-occupying lesions. Standardized application of the WHO reporting framework enables objective ROM stratification and facilitates effective clinical decision-making. FNAC remains a vital diagnostic tool in the evaluation of hepatic masses, especially in resource-limited or time-sensitive settings.