A nomogram-based risk stratification strategy to optimize central lymph node dissection in cN1a papillary thyroid cancer with Hashimoto’s thyroiditis

Background: XXXXXXXXXXXX. This study aimed to investigate the risk factors for true central lymph node metastasis (CLNM) in patients with cN1a stage papillary thyroid carcinoma (PTC) complicated by Hashimoto’s thyroiditis (HT) and to explore management strategies for low-risk patients.

Methods: We retrospectively analyzed patients diagnosed with cN1a stage PTC at our hospital from 2015 to 2025. General information and ultrasound characteristics were collected, and patients were categorized based on their HT status and CLNM status. Logistic regression analysis was performed, and a predictive nomogram for CLNM was developed and validated.

Results: HT significantly increased the false-positive rate of CLNM (24.7% vs. 33.3%, P<0.05) and total number of lymph nodes dissected {7 [interquartile range (IQR), 4–11] vs. 6 (IQR, 3–10), P=0.04} in cN1a PTC patients, but did not increase the number [1 (IQR, 0–3.75) vs. 2 (IQR, 1–5), P=0.28] or proportion [0.2 (IQR, 0–0.6) vs. 0.5 (IQR, 0.08–0.83), P=0.02] of metastatic lymph nodes. Gender, age, tumor size, thyroid lobe lesions, lymph node round shape, cystic change, and microcalcification were identified as independent risk factors for CLNM in cN1a PTC patients with HT. In patients with a risk stratification of very low risk, the risk of developing true CLNM is less than 0.05.

Conclusions: Preoperative cN1a staging is frequently confounded by HT-related inflammatory lymphadenopathy, necessitating a more nuanced diagnostic approach. Our nomogram effectively stratifies the risk of true CLNM in this population, and serves as an auxiliary tool to provide decision-making advice for central lymph node dissection (CLND).