<prompt> The neuroendocrine carcinoma arising from parafollicular C cells of thyroid is:Papillary carcinomaFollicular carcinomaMedullary carcinomaAnaplastic carcinoma  <response>: MEDULLARY CARCINOMA OF THE THYROID MCTThese tumours arise from parafollicular C cells which are derived from ultimobranchial bodies and not from thyroid foillicle.These tumours present in two different ways.Sporadic is common, seen in about 80-90 of cases.Familial variety present as a part of multiple endocrine neoplasia MEN.MEN Type IPituitary adenomaParathyroid adenomaPancreatic adenomaMEN Type IIaParathyroid adenomaPhaeochromocytomaMedullary carcinoma of thyroidWhen it is associated with mucocutaneous neuromas involving lips, tongue, eyelids, it is called Sipple syndrome, with an occasional marfanoid habitus MEN type IIbIt has got a characteristic amyloid stroma These tumours are not TSH-dependent and do not take up radioactive iodine Hormones produced by MCTCalcitonin ProstaglandinsSerotonin 5-HT, ACTHSpreadBoth by lymphatics and blood, thus, worsening the prognosis.Key Concept:Medullary Carcinoma arises from parafollicular C cells which are derived from ultimobranchial bodies and not from thyroid follicle. The medullary carcinoma produces hormones such as Calcitonin, Prostaglandins and serotonin.Reference: Manipal Manual of Surgery 4th ed page no 348 