Fibrosis-Driven Surgical Risk After Thyroid Nodule Ablation: Quantitative Clinicopathological Determinants of Complications in Post-Ablative Thyroidectomy-A Retrospective Cohort Study.

Abstract

Thermal ablation is increasingly used for selected benign and low-risk thyroid nodules, yet some patients still require thyroidectomy for regrowth, persistent symptoms, or new oncologic concern. The surgical and pathological impact of ablation-induced remodeling remains incompletely defined. We aimed to characterize postablation thyroidectomy outcomes and identify histological correlates of perioperative morbidity. We conducted a single-center retrospective cohort study of patients undergoing thyroidectomy after radiofrequency or ethanol ablation (2021-2025). Clinical and ablation-related variables were collected, and intraoperative neuromonitoring was routinely used. Primary outcomes were recurrent laryngeal nerve (RLN) palsy, reoperative hematoma, and hypoparathyroidism. Surgical specimens underwent blinded dual-pathologist assessment with semiquantitative scoring of sclerosis, necrosis, and residual viability, from which a maturation index was derived. Associations with complications were analyzed using nonparametric methods. Outcomes were descriptively compared with a contemporaneous nonablated cohort for contextual purposes. Thirty-one patients were included. Postoperative complications occurred in 22.6% of ablated cases. Histological analysis demonstrated moderate sclerosis (19.2%), necrosis (14.6%), and high residual viability (66.1%), with frequent pericapsular inflammatory changes and preserved capsule integrity. Sclerosis was the only parameter significantly associated with postoperative complications (30.0% vs. 16.9% and p = 0.008), whereas nodule size, ablation-to-surgery interval, and incidental carcinoma were not predictive. The maturation index increased with time after ablation but did not discriminate complication risk. Exploratory fibrosis-weighted metrics suggested potential risk thresholds, although these findings remain hypothesis-generating given the limited sample size. Thyroidectomy after prior ablation is feasible in experienced centers but may be technically demanding and associated with modestly increased procedural complexity. Mature sclerosis represents the principal histological correlate of perioperative morbidity, linking fibrotic remodeling to operative risk. These findings support centralization of postablation thyroid surgery in high-volume units with routine neuromonitoring and specialized pathology and highlight the need for larger prospective studies to validate fibrosis-based risk stratification tools.