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.