Classifying Liver Cytology Using the WHO Reporting System: Institutional Experience and Malignancy Risk Assessment.

Aim: The World Health Organization's (WHO) Reporting System for Liver Cytopathology aims to standardize communication with clinicians globally to improve patient management. Our study reclassifies liver cytology reports based on the WHO classification and assesses the risk of malignancy (ROM) in each category.

Methods: Liver cytology reports from 2019 to 2023 were retrieved to obtain demographic details, clinical data, cytology, and surgical follow-up (SFU). Cytology diagnoses were reclassified using the WHO classification. ROM was analyzed based on SFU.

Results: Our study had 976 cases, age ranged from 1-96 years, with an average age of 67 years. Male: female ratio was 1:1. Majority of lesions (400/525, 76%) were less than 5 cm. Location of the lesion was available in 595 cases, with right lobe being the most common (64%; n = 383), followed by left lobe (36%, n = 212). 883 cases (90%) underwent rapid onsite evaluation. Reclassification using the WHO classification system into 5 categories included non-diagnostic (n = 79), benign (n = 117), atypical (n = 25), suspicious for malignancy (n = 6) and malignant (n = 749). Thirty-one cases (3%) had cytology follow up, 71(7.3%) had SFU. The ROM in the SFU cohort was 17% (1/6; 95% CI: 10%-76%) in non-diagnostic, 23% (3/13, 95% CI: 15.4%-30.6%) in benign and 100% in atypical (3/3, 95% CI: 88%-100%), suspicious for malignancy (2/2, 95% CI: 50%-100%) and malignant(47/47, 95% CI: 99.5%-100%) categories. Repeat FNA yielded malignant upgrade rates of 80% (4 out of 5) in non-diagnostic and 75% (3 out of 4) in atypical categories.

Conclusion: We present the values of ROM in the various categories of the WHO Reporting System for Liver Cytopathology using a large cohort of cases. Repeat sampling is recommended in non-diagnostic and atypical categories based on an increase in malignant upgrades in these categories.