Thyroid cancers

1. Big picture

Thyroid cancer usually presents as a thyroid nodule. Most thyroid nodules are benign, but the examiner wants you to recognize the danger signs, know when to do ultrasound-guided fine-needle aspiration biopsy (FNA), and distinguish the main cancer types:

Papillary and follicular = differentiated thyroid cancers from follicular cells → often iodine-sensitive → surgery ± radioactive iodine (RAI) + thyroglobulin follow-up. Medullary = parafollicular C-cell tumor → calcitonin marker → RET/MEN2 association → no RAI. Anaplastic = rapidly enlarging invasive thyroid mass in older patient → emergency airway risk → very poor prognosis.

Risk factors include c