Extrahepatic soft tissue mimicking applicator-tract implantation after percutaneous radiofrequency ablation of hepatic malignancy

OBJECTIVE. The purpose of our study was to identify extrahepatic soft tissue mimicking applicator-tract implantation after percutaneous radiofrequency ablation of hepatic malignancy on triple-phase dynamic CT. MATERIALS AND METHODS. A database was reviewed for 131 patients who underwent percutaneous radiofrequency ablation for treatment of a hepatic tumor over a 3-year period. Patients who developed extrahepatic soft tissue adjacent to the previous ablation zone mimicking applicator-tract implantation were identified. The clinical features of patients, characteristics of extrahepatic soft tissue on CT, soft-tissue changes on follow-up CT, and histopathologic results were evaluated. RESULTS. Extrahepatic soft tissue developed in five patients (3.8%) at 2-8 months after percutaneous radiofrequency ablation. Extrahepatic soft tissue showed progressive enhancement during the delayed phase of dynamic CT. Four lesions were completely resolved without any treatment. However, one lesion was enlarged and xanthogranulomatous inflammation was diagnosed by percutaneous biopsy. Univariate analysis showed that an index tumor with a subcapsular location and a prior biopsy had high odds ratios. CONCLUSION. The possibility of a benign inflammatory lesion should be considered when extrahepatic soft tissue showing radiologic findings similar to applicator-tract implantation develops after radiofrequency ablation of a hepatic tumor.