Which lymph node shape is concerning for malignancy in the post-thyroidectomy neck?

Malignant lymph nodes are often round in shape (short axis/long axis ratio approaches 1), while benign lymph nodes are typically oval (short axis/long axis ratio < 0.5). Rounded shape in post-thyroidectomy patients raises suspicion for metastatic disease.

According to AIUM and ACR Thyroid Imaging Guidelines:

“A rounded lymph node shape is suspicious for malignancy, especially in patients with thyroid cancer.”