Fine needle aspiration cytodiagnosis of liver tumors

OBJECTIVE: To present our experience with liver fine needle aspiration (FNA) diagnosis and the adjunctive use of cell blocks with reticulin stain. STUDY DESIGN: The authors reviewed the results of cytopathologic diagnosis obtained by FNA biopsy over a 1-year period, from January 2000 to December 2000, in patients who presented primarily with ultrasonographically suspected liver nodules. FNA smears from 936 patients and cell blocks from 796 patients were reviewed. RESULTS: Among the 936 aspirates studied, the most common malignancy was hepatocellular carcinoma (HCC), which was diagnosed in 427 cases (45.6%), followed by metastatic adenocarcinoma, with 52 cases (5.6%). The concurrent cell block was available in 796 cases. Among them, 574 (72.1%) contained sufficient tissue for diagnosis. Combining analysis of cytologic and histologic specimens, the sensitivity of ultrasound-guided FNA for diagnosis of liver tumors was 85.1% and the specificity 98.7%. The results were better than isolated cytologic analysis, which gave a sensitivity of 78.4% and specificity of 97.4%. The lower diagnostic accuracy of cytology resulted mainly from its lower ability to distinguish well-differentiated HCC from benign lesions. In the cell block sections with reticulin stain, all HCCs showed a decreased or absent reticulin pattern, whereas all the benign hepatocellular lesions usually had a normal trabecular reticulin framework. CONCLUSION: FNA cytology assisted by cell block examination can be an accurate and minimally invasive method for the definitive pathologic diagnosis of primary benign and malignant liver masses and for confirmation of tumors metastatic to the liver. In addition, reticulin staining should be part of the routine assessment of cell blocks. It enhances diagnostic accuracy, particularly for well-differentiated HCC.