The Utility of Fine Needle Aspiration Cytology in the Assessment of Hepatic Lesions

Abstract

Introduction: Fine Needle Aspiration Cytology (FNAC) is a less invasive, rapid and less expensive diagnostic technique which was initially used for only readily palpable masses and superficial organs. In recent years however, modern imaging techniques like Ultrasonography (USG) and Computed Tomography (CT) have made it possible to use this procedure for inaccessible lesions and deeper organs like the liver. Aim: To evaluate the utility of FNAC in the assessment of neoplastic and non-neoplastic hepatic lesions and to determine its diagnostic accuracy particularly in malignant hepatic neoplasms. Materials and Methods: The combined analysis of retrospective and prospective data was conducted over a period of 22 years (from January 1998 to December 2019) in the Department of Pathology, Goa Medical College, Goa, India, on 535 patients who presented clinically and radiologically with hepatic lesions. The Fine Needle Aspirations (FNAs) were performed under ultrasound and CT guidance. The cytology smears were then stained with Haematoxylin and Eosin (H&E) and May Grunwald Giemsa (MGG) stains. A cytohistopathological correlation was performed manually wherever possible with the available data. The overall diagnostic accuracy of FNAC as well as the diagnostic sensitivity of the procedure in detecting malignant hepatic lesions and its positive predictive value was calculated. The chi-square distribution of the categories of cytological reporting and of the various cytopathological diagnosis among the diagnostic aspirates was also studied to find the statistical significance. Results: Among the 535 patients studied, 386 (72.1%) cases were diagnostic of which 76 were non-neoplastic and 310 (57.9%) were neoplastic lesions. The remaining 149 cases contributed to the non diagnostic category. The distribution of the diagnostic aspirates was statistically significant (p<0.0001). This series showed a male preponderance with most of the patients in the 51-60 years age group. Pyogenic abscess of the liver was the commonest non- neoplastic and non malignant lesion (non-neoplastic lesion+Benign neoplasms) and Hepatic metastasis was the commonest neoplastic and malignant lesion. The Chi-square statistics for the same was also significantly high (p<0.0001). While adenocarcinoma was the most frequent metastasis morphologically, the commonest site of known primary cancer with hepatic metastasis was the gastrointestinal tract. Cytohistopathological correlation was available in 72 cases. The overall diagnostic accuracy of FNAC in this study was 90% and the diagnostic sensitivity for malignant hepatic lesions was 98% with a positive predictive value of 94%. Conclusion: Guided FNAC of liver was thus confirmed as a safe procedure that was useful in the successful diagnosis of hepatic lesions especially malignancies.