<prompt> Which is the least common thyroid malignancy?Papillary carcinomaFollicular carcinomaMedullary carcinomaAnaplastic carcinoma  <response>: Ans. is d i.e., Anaplastic carcinoma Least common type of thyroid carcinoma is anaplastic type. Most common type of thyroid carcinoma is papillary carcinoma 75-85 followed by follicular carcinoma 10-15, medullary carcinoma 5 and anaplastic carcinoma 5. 