ABSTRACT

Radiofrequency ablation (RFA) is an effective and widely used percutaneous treatment for hepatocellular carcinoma (HCC), particularly in patients awaiting liver transplantation. However, despite technological advances, tumor seeding along the needle tract remains a rare but clinically significant complication. A 59-year-old male patient with Child-Pugh A cirrhosis secondary to hepatitis B virus/hepatitis D virus infection and a prior diagnosis of HCC was found to have a newly developed 18×12 mm subcapsular lesion in segment VI of the liver on follow-up magnetic resonance imaging (MRI). RFA was performed prior biopsy. Three months later, MRI demonstrated newly developed nodular lesions along the ablation tract surrounding the ablation zone, highly suggestive of needle-tract seeding. The patient received systemic therapy including lenvatinib, sorafenib, and regorafenib, as well as repeated RFA and transarterial chemoembolization procedures. However, liver transplantation could not be performed because a suitable donor was unavailable, and the patient remains under ongoing oncologic follow-up. Although the overall incidence of neoplastic seeding after RFA is low (0.6-1.4%), several factors—including subcapsular tumor location, poor differentiation, large tumor size, elevated alpha-fetoprotein levels, and pre-ablation biopsy—have been associated with increased risk. Needle tract ablation and careful patient selection have been shown to reduce this risk. Additionally, novel imaging modalities such as indocyanine green near-infrared fluorescence may facilitate intraoperative detection and complete excision of seeded foci. This case suggests that tumor seeding may occur after RFA even in the absence of pre-procedural biopsy. In patients with subcapsular lesions, meticulous procedural technique, careful evaluation of risk factors, and close post-procedural surveillance are essential for optimizing clinical outcomes.

Introduction

The use of percutaneous ablative techniques for the treatment of liver tumors has increased substantially over the past decades. Percutaneous ethanol injection (PEI), radiofrequency ablation (RFA), and microwave ablation (MWA) are viable curative techniques for hepatocellular carcinoma (HCC) (1).

Studies have shown that percutaneous treatment of HCC is a cost-effective bridging strategy in patients whose expected waiting time for liver transplantation exceeds six months (2).

However, when tumors are located in specific anatomical regions, such as beneath Glisson’s capsule, in an exophytic position, or adjacent to critical structures, percutaneous treatment may be associated with complications including incomplete ablation, hemorrhage, injury to adjacent organs, and needle-tract seeding (3). Subcapsular location, poor tumor differentiation, tumor size greater than 3 cm, elevated serum alpha-fetoprotein (AFP) levels, and diagnostic biopsy before ablation have been reported as risk factors for needle-tract seeding (4-6).

Case Report

A 59-year-old male patient had been under follow-up since 2002 for HBV, HDV, and chronic liver disease. The patient progressed to Child-Pugh class A cirrhosis, and he was diagnosed with HCC 6.5 years ago. The patient had previously undergone transarterial chemoembolization and systemic therapy for HCC. He was subsequently followed with serial magnetic resonance imaging (MRI) examinations. His laboratory tests were carcinoembryonic antigen, 10 ng/mL; carbohydrate-related antigen 19-9, 28 U/mL; and AFP, 2411 ng/mL.

During follow-up MRI, a subcapsular lesion measuring approximately 18×12 mm was detected in segment VI of the right hepatic lobe. The lesion was considered suspicious for a new HCC lesion in a patient with a known history of HCC and markedly elevated AFP levels. Positron emission tomography/computed tomography was performed as part of the pre-transplant evaluation and to further characterize the lesion. Because no significant FDG uptake was observed, histopathological confirmation or further imaging studies were recommended, considering that well-differentiated HCC may demonstrate low FDG avidity. Despite the recommendation for further diagnostic evaluation, RFA was subsequently performed for the segment VI lesion at another medical center. No biopsy was performed either before or after the ablative procedures.

Three months after the RFA, MRI demonstrated a 27×22 mm ablation zone in segment VI, accompanied by changes consistent with post-procedural hemorrhage (Figure 1). No significant residual or recurrent tumor was detected. One month later, newly developed nodular lesions measuring 10 mm along the capsular surface and 11 mm within the adjacent superior adipose tissue were detected near the RFA zone. Based on their anatomical continuity with the ablation tract and interval growth on serial MRI examinations, these lesions were considered radiologically suspicious for needle-tract seeding (Figure 2). A significant increase in lesion size was observed on subsequent MRI examinations.

The patient was subsequently referred to the oncology department, and systemic treatment with lenvatinib with pembrolizumab was initiated. As the lesion progressed, sorafenib was started, then switched to regorafenib. Subsequently, repeat RFA and transarterial chemoembolization were performed, resulting in partial regression of the lesions. Following these interventions, the AFP level decreased to 1400 ng/mL, and treatment with regorafenib was continued. Liver transplantation could not be performed because a suitable donor was not available. The patient remains under ongoing clinical and radiological follow-up.

Written informed consent was obtained from the patient for the publication of this case report and any accompanying images.

Discussion

Needle-tract seeding is a recognized complication of biopsy and percutaneous ablative techniques for HCC, including RFA, PEI, and MWA. Although reported rates vary among studies, the overall incidence remains low.

Llovet et al. (3) reported a tumor seeding rate of 12.5% after RFA for HCC, which is considerably higher than that reported in subsequent studies. Takamori et al. (7) reported a seeding rate of 5.1% in patients who underwent diagnostic biopsy before RFA. The overall incidence of tumor seeding after liver biopsy for HCC was reported to be approximately 2.7% (8). Moreover, in a multicenter study involving 1,314 patients, Livraghi et al. (1) reported similar seeding rates among the three participating centers (0.7%, 0.9%, and 1.4%). In another study involving 60 cirrhotic patients with subcapsular HCC treated with RFA or MWA, needle-tract seeding occurred in only one patient, who had undergone biopsy before ablation (9). According to the systematic review by Stigliano et al. (10), reported seeding rates were 2.29% after biopsy alone, 1.4% after PEI combined with biopsy, 0.61% after RFA without biopsy, 0.95% after RFA with biopsy, and 0.72% for biopsied and subsequently ablated liver nodules, including non-HCC lesions.

Studies support that RFA is an effective and safe bridging therapy until transplantation in patients with HCC (2). However, because needle-tract seeding may adversely affect clinical outcomes, careful patient selection and the implementation of preventive measures are warranted (11).

It has been shown in an experimental animal model that needle tract ablation in HCC reduces the seeding rate (12). In another study, when RFA was performed on subcapsular HCC, no tract seeding was observed when needle tract ablation was performed on tumors 4 cm and smaller (13). Intraoperative use of indocyanine green near-infrared fluorescence imaging has enabled the detection of seeded tissues and peritoneal implants along the RFA needle. This technique enables complete surgical excision of all tumor-positive areas, along with histopathological confirmation of HCC in the resected specimens (14).

The present case should be interpreted cautiously because histopathological confirmation of either the treated segment VI lesion or the subsequently developed nodules was unavailable. Nevertheless, the appearance of new nodules along the presumed needle trajectory shortly after RFA and their progressive enlargement on serial imaging strongly suggested radiologically presumed needle-tract seeding. Therefore, the diagnosis in this case remains presumptive and based primarily on imaging findings and temporal association with the intervention.

Although histopathological confirmation was unavailable, alternative diagnoses such as post-ablation inflammatory nodules or hemorrhagic changes were considered less likely because the lesions developed along the presumed needle trajectory and demonstrated progressive enlargement on serial MRI examinations.

Conclusion

Although no diagnostic biopsy was performed, radiologically presumed needle-tract seeding developed in our patient, suggesting that subcapsular tumor location and markedly elevated AFP levels may have contributed to the development of this complication.

Whenever possible, the diagnosis of HCC should rely on established radiological and clinical criteria to avoid unnecessary biopsy and its potential complications. These findings highlight the importance of meticulous procedural technique and careful patient selection in minimizing the risk of tumor dissemination after percutaneous interventions for HCC. The use of adjunctive technologies, such as tract ablation and intraoperative fluorescence imaging, may improve safety and oncologic outcomes in this patient group.