Cold Thyroid Nodule: The Next Step

D. Ultrasound-guided fine needle aspiration biopsy (FNA) — cold nodules carry ~15% malignancy risk

A 'cold' thyroid nodule (absent or decreased uptake relative to surrounding thyroid) carries approximately a 15% risk of malignancy. While most cold nodules are benign (cysts, benign adenomas, colloid nodules, Hashimoto's nodules), the significant malignancy risk mandates tissue sampling. Ultrasound-guided fine needle aspiration (FNA) biopsy is the standard of care for evaluating cold thyroid nodules, especially those with suspicious ultrasound features (microcalcifications, irregular margins, hypoechoic, taller-than-wide on transverse view). Hot nodules (<1% malignancy) do NOT require FNA.