Objective:

To create and authenticate a nomogram that combines tumor spatial positioning with clinical and ultrasonographic characteristics to forecast central lymph node metastasis (CLNM) in unifocal papillary thyroid microcarcinoma (PTMC).

Key Findings:

• Age ≤ 38 years, tumor size > 0.95 cm, presence of microcalcifications, suspicious central/lateral lymph nodes, tumor located in the isthmus, and tumor situated in the middle/inferior pole adjacent to the posterior capsule are independent risk factors for CLNM.
• Hashimoto's thyroiditis is identified as a protective factor against CLNM.
• The nomogram achieved AUCs of 0.772 in training and 0.728 in validation.

Interpretation:

The nomogram effectively predicts CLNM risk based on tumor characteristics, aiding in surgical decision-making.

Limitations:

• Retrospective nature may introduce selection bias.
• External validation is needed to confirm generalizability.

Conclusion:

The nomogram based on spatial location is a valuable preoperative tool for assessing CLNM risk, facilitating tailored surgical planning and reducing overtreatment in unifocal PTMC.