<prompt> A biopsy from a mass in front of the neck revealed parafollicular cells. How do you follow up?CalcitoninT4ThyroxineThyroglobulin  <response>: Biopsy from the mass in front of the neck revealed parafollicular cells indicating that its a case of Medullary carcinoma of the thyroid. Medullary carcinoma of the thyroid MTC: It is a distinct thyroid carcinoma that originates in the parafollicular C cells of the thyroid gland. These C cells produce calcitonin. Hence it is used for follow up of these patients 