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

Abstract

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.

Keywords: ablation; contrast media; radiofrequency; thyroid carcinoma; ultrasonography.

Figure 1

Radiofrequency ablation (RFA) treatment and follow‐up of one case of papillary thyroid microcarcinoma with chronic lymphocytic thyroiditis. (A) A hypoechoic nodule sized 0.4 × 0.5 × 0.4 cm, with irregular margins and microcalcifications was displayed in the right thyroid lobe (arrow). (B) Uneven and irregular hypo‐enhancement in the nodule was observed by contrast‐enhanced ultrasound (CEUS) (arrow, left image). (C) During RFA, the nodule was covered by a hyperechoic area (arrow) on US. (D) Immediately after RFA, the ablation area was showed completely no enhancement by CEUS, and its size (0.7 × 1.1 × 1.0 cm) was larger than the initial nodule size. (E) One month after RFA, the ablation area decreased in size to 0.9 × 0.8 × 0.5 cm. (F) Three months after RFA, the ablation area decreased to 0.6 × 0.5 × 0.6 cm. (G) Six months after RFA, the ablation area decreased to 0.3 × 0.2 × 0.3 cm. (H) The ablation area could not be identified on both US and CEUS. (I) Before RFA, the pathologic examination of this nodule showed the presence of papillary thyroid carcinoma accompanied by chronic lymphocytic thyroiditis. (J) Three months after RFA, pathology showed degenerated and necrotic follicular epithelia, interstitial fibrous tissue hyperplasia, and hyaline degeneration in the ablation lesion, with lymphocyte infiltration and multinucleated giant cell reaction in the adjacent thyroid tissue. No residual cancer was found

Figure 2

Changes in ablation zone volume in PTMC cases with and without CLT at each follow‐up. PTMC, papillary thyroid microcarcinoma; CLT, chronic lymphocytic thyroiditis