Surgical and Pathological Challenges in Thyroidectomy after Thermal Ablation of Thyroid Nodules.

Background: Thermal ablation is a minimally invasive treatment for benign thyroid nodules, but its impact on subsequent thyroidectomy and pathological evaluation is uncertain. This study investigates whether preoperative ablation complicates thyroidectomy and poses challenges for pathological diagnosis. Study Design: This retrospective cohort study used prospectively collected institutional registry data on patients with benign thyroid nodules who underwent thyroidectomy after prior radiofrequency ablation. Perioperative outcomes, including thyroidectomy difficulty scale (TDS) and macroscopic adhesion score (MAS), were compared with a control group without prior ablation. Histopathological and cytological changes within the ablated zone and periphery were also evaluated. Results: This study included 165 patients, with 145 in the nonablation group and 20 in the postablation group (17 females, mean age 53.4 years, mean nodule size 4.4 cm, mean interval between ablation and thyroidectomy 29.5 months). Compared with the nonablation group, the ablation group had longer operative time (99.5 vs. 69.5 minutes, p < 0.05), higher TDS (9 vs. 6, p < 0.05), more severe MAS (anterior 50.0% vs. 16.6%, p < 0.05; posterior: 35.0% vs. 16.6%, p < 0.05), and increased incidental parathyroidectomies (10.7% vs. 1.6%, p < 0.05). Histopathologically, the ablated area showed acellular hyalinization (95%), coagulative necrosis (60%), and chronic inflammation (85%). Both central and peripheral regions displayed cytological alterations (nuclear enlargement, focal chromatin clearing, and clear-cell change). Challenges in defining tumor capsule integrity were noted in eight follicular neoplasms, complicating the diagnosis of three follicular carcinomas and two follicular tumors of uncertain malignant potential. Conclusions: Thermal ablation of thyroid nodules may be associated with increased surgical difficulty and adhesion formation during subsequent thyroidectomy. Additionally, ablation-induced tissue alterations can potentially complicate pathological diagnosis. However, due to the small number of study cases, further confirmatory research is needed.