Histopathologic evaluation of tissue extracted on the radiofrequency probe after ablation of liver tumors: preliminary findings

OBJECTIVE: Our aim was to evaluate the histologic characteristics of tissue extracted on the probe immediately after radiofrequency ablation of malignant tumors in the liver. MATERIALS AND METHODS: From April to December 2001, 20 radiofrequency ablations were performed in 19 patients with primary (n = 17) and metastatic (n = 2) liver masses. Track ablation according to device protocol was performed after each ablation. Tissue was adherent to the probe after all radiofrequency probe passes. All pieces of tissue found on the probe were collected and preserved in formalin. RESULTS: Tissue was examined by the study pathologist. In eight (40%) of 20 specimens, coagulation necrosis was present. In five (25%) of 20 specimens, possibly nonviable tissue was extracted, although some cell characteristics were identified. In seven (35%) of 20 specimens with hepatocellular carcinoma, possibly viable tissue was found. Five specimens were identified as hepatocellular carcinoma, and two, as cirrhotic nodules. CONCLUSION: Histopathologic evaluation of the tissue extracted on the radiofrequency probe after ablation is feasible. This study showed that coagulation necrosis was clearly present in at least 40% of the patients, which proves that nonviable tissue can be seen immediately after ablation. Whether this pathologic finding has prognostic value is not known.