<prompt> 40-year old female presented with neck swelling. Gross and histology is shown below. What is your diagnosis?Medullary carcinoma thyroidHashimotos thyroiditisAnaplastic carcinomaFollicular carcinoma  <response>: Ref. Robbins Pathology. 9th edition. Page. 1099Medullary carcinoma thyroidGrossSingle or multipleTypically nonencapsulatedSolid, gray tan yellow, firm, may be infiltrativeMicroscopyRound, polygonal or spindle cells in nests, cords or follicles, defined by sharply outlined fibrous bandsTumor cells have granular cytoplasm and uniform round oval nuclei with punctate chromatinStroma has amyloid deposits from calcitonin, prominent vascularity with glomeruloid configuration or long cords of vessels, coarse calcifications IHC Calcitonin 