Effect of chronic lymphocytic thyroiditis on the efficacy and safety of ultrasound‐guided radiofrequency ablation for papillary thyroid microcarcinoma

BACKGROUND: Chronic lymphocytic thyroiditis (CLT) is an autoimmune disease commonly associated with papillary thyroid carcinoma characterized by a smaller primary tumor size at presentation. The efficacy and safety of ultrasound-guided radiofrequency ablation (RFA) for papillary thyroid microcarcinoma (PTMC) coexisting with CLT is still unknown. METHODS: Sixty patients with unifocal PTMC were enrolled and classified into PTMC and PTMC+CLT groups (n = 30/group). CLT was diagnosed histopathologically. The ablation area exceeded the tumor margins, and was evaluated by US and contrast-enhanced US (CEUS) for residual tumor to prevent recurrence. Three months after ablation, US-guided core-needle biopsy was performed to assess the presence of residual and recurrent cancer. Preoperative and postoperative data on patients and tumors were recorded and analyzed. RESULTS: There were no differences between groups in age, sex, preoperative tumor volume, ablation time, or ablation power (P > 0.05). There was also no significant difference in postoperative ablation zone volume between the groups at the 1-, 3-, 6-, 12-, and 18-month follow-ups (P > 0.05). The volume reduction rate significantly differed between the two groups at month 3 (P = 0.03). The ablation area could not be identified on US and CEUS at 9.8 ± 5.0 and 10.0 ± 4.8 months in the PTMC and PTMC + CLT groups, respectively (P = 0.197). No serious complications occurred during and after ablation. No residual cancer cells were found on biopsy after ablation. CONCLUSIONS: RFA was effective in patients with PTMC+CLT, and its therapeutic efficacy and safety were similar to those in patients with PTMC without CLT.