Medullary carcinoma thyroid arises from ?

Ans. is 'a' i.e., Parafollicular cells The unique feature of Medullary carcinoma thyroid is that unlike other carcinomas of thyroid they are not derived from the cells of the thyroid follicle, instead they are derived from calcitonin secreting parafollicular cells (C cells) which are neural crest derivatives. Thyroid neoplasm can arise from any of the cell types found within thyroid gland i.e. thyroid follicular cells, parafollicular cells (C cells), lymphocytes and stromal and vascular elements.