Papillary thyroid carcinomas spread lymphatically. It is not uncommon to find metastasis in lymph nodes on the neck locally and regionally, even next to small primary tumors. Up to 50% of patients have metastasis at the time of the diagnosis. Distant metastasis mainly localize in the lungs and bone.
Follicular thyroid carcinomas spread mainly hematogenically and usually to the bone and/or lungs.
Anaplastic thyroid carcinoma metastasizes to local lymph nodes regionally, mediastinally, as well as to the lungs and brain.