<prompt> Least common thyroid malignancy is:PapillaryFollicularMedullaryAnaplastic  <response>: Least common thyroid malignancy is anaplastic. Most common thyroid malignancy - Papillary Follicular Medullary Anaplastic Papillary carcinoma - 80 occur in Iodine-sufficient areas and predominant thyroid cancer in children and individuals exposed to external radiation. Follicular carcinomas - 10 of thyroid cancers and occur more commonly in iodine-deficient areas. MTC- about 5 Anaplastic carcinoma- about 1 