Lessons in IR: Track Metastasis after Percutaneous Ablation of Hepatocellular Carcinoma

A 61-year-old woman with hepatitis B underwent multiphase contrast-enhanced computed tomography (CT) for hepato-cellular carcinoma (HCC) surveillance. Imaging revealed a 3.1-cm solitary mass in Segment 6 (Fig 1a, arrow) characterized by Liver Reporting & Data System (LI-RADS) category 5 features diagnostic for HCC. Curative intent radiofrequency (RF) ablation was performed under moderate sedation using a 14-gauge RF ablation probe (Starburst Talon; AngioDynamics, Latham, New York) and real-time ultrasound guidance (Fig 1b). Two overlapping 9 -minute and 4-minute ablations were performed, with the probe tines extended to 4 and 3 cm, respectively. Liver track ablation was performed during electrode withdrawal. One -month postablative CT demonstrated complete response as per the modified Response Evaluation Criteria in Solid Tumors (Fig 1c, arrow). Although complete response was maintained at 3-month (Fig 1d) and 6-month (Fig 1e) imaging, CT also revealed an enlarging, solid, enhancing nodule in the intercostal space along the RF ablation tract (red circles in Fig 1d, e), consistent with a track metastasis. Both the right hepatic lobe-to include the treated HCC-and the track metastasis were resected 7 months after ablation. Follow-up imaging up to 7 years (Fig 1f) showed no disease recurrence. Institutional review board approval was not required for this case report. granulation nodule (which can be distinguished by temporal evolution of the finding or biopsy). center dot Risk factors for track metastasis include subcapsular or deep tumor location, primary liver cancer (HCC), poorly differentiated carcinoma, elevated alpha-fetoprotein level, multiple needle insertions, needle biopsy before ablation, and a larger-caliber needle/ applicator (3).