Accuracy of cytology vs. microbiopsy for the diagnosis of well-differentiated hepatocellular carcinoma and macroregenerative nodule. Definition of standardized criteria from a study of 100 cases.

OBJECTIVE: To determine the accuracy of ultrasound (US)-guided fine needle aspiration (FNA) for the diagnosis of well-differentiated hepatocellular carcinoma (wd HCC) and macroregenerative nodule (MRN) and to identify the most useful cytologic and histologic criteria to distinguish between those two diagnoses. STUDY DESIGN: Cytologic and histologic specimens of 50 wd HCC and 50 MRN were reviewed blindly and the diagnosis compared to the final clinical diagnosis. Twenty-eight cytologic and 25 histologic criteria were examined and subjected to statistical analysis. RESULTS: Among 100 cases studied, the final diagnosis was available for 43. In those 43 cases, combining analysis of cytologic and histologic specimens, the sensitivity of US-guided FNA was of 75% and the specificity 100%. Cytologic analysis was better than isolated histologic analysis, with a sensitivity of 75% vs. 68%, respectively. Sensitivity of cytologic diagnosis was lower for smaller nodules and for those located in poorly accessible hepatic segments. With the use of stepwise logistic regression analysis, four cytologic features (increased nuclear/cytoplasmic ratio, cellular monomorphism, nuclear crowding, loss of bile duct cells) and four histologic features (increased nuclear/cytoplasmic ratio, decreased Kupffer cells, cellular monomorphism, increased trabeculae thickness) were identified as predictive of HCC. CONCLUSION: This study demonstrated that FNA with US guidance can provide an accurate diagnosis of wd HCC and MRN. The limiting factor of the method is sampling error, especially for small HCC and nodules located in poorly accessible hepatic segments.