Amyloid deposits are seen in which thyroid malignancy?
Ans: A (Medullary Ca) Ref: Robbins Pathologic Basis of Disease, 8th edition.Explanation:"Acellular amyloid deposits, derived from altered calcitonin polypeptides, are present in the adjacent stroma in many cases of Medullary carcinoma of thyroid" Ref: RobbinsMedullary Carcinoma of ThyroidThese are neuroendocrine neoplasms derived from the parafollicular cells, or C cells,Accounts for approximately 5% of thyroid neoplasms.Medullary carcinomas, similar to normal C cells, secrete calcitonin, the measurement of which plays an important role in the diagnosis and postoperative follow-up of patients.May also secrete other polypeptide hormones, such as serotonin, ACTH, and vasoactive intestinal peptide (VIP).About 70% of tumors arise sporadically.The remainder occurs in the setting of MEN syndrome 2A or 2B or as familial tumors without an associated MEN syndrome.Activating point mutations in the RET protooncogene (chr 10) - both familial and sporadic medullary carcinomas.Cases associated with MEN types 2A or 2B occur in younger patients.Familial medullary carcinomas arises in 4th - 5th decade.MorphologySporadic medullary thyroid carcinomas present as a solitary nodule.In contrast, bilaterality and multicentricity are common in familial cases.Larger lesions often contain areas of necrosis and hemorrhage and may extend through the capsule of the thyroid.The tumor tissue is firm, pale gray to tan. and infiltrative.Microscopically, medullary carcinomas are composed of polygonal to spindle-shaped cells, which may form nests, trabeculae, and even follicles.Small, more anaplastic cells are present in some tumors and may be the predominant cell type. Acellular amyloid deposits derived from calcitonin polypeptides are present in adjacent stroma.Calcitonin is readily demonstrable within the cytoplasm of the tumor cells and in stromal amyloid by immunohistochemical methods.One of the peculiar features of familial medullary cancers is the presence of multicentric C-cell hyperplasia in the surrounding thyroid parenchyma, a feature that is usually absent in sporadic lesions.Foci of C-cell hyperplasia are believed to represent the precursor lesions from which medullary carcinomas arise*Clinical CourseSporadic cases presents with mass in the neck and dysphagia or hoarseness.Paraneoplastic syndrome can occur, caused by the secretion of a peptide hormone (e.g., diarrhea due to the secretion of VIP, or Cushing syndrome due to ACTH).Notably, hypocalcemia is NOT a prominent feature, despite the presence of raised calcitonin levels.Secretion of carcinoembryonic antigen (CEA) by the neoplastic cells is a useful biomarker.
Medullary Ca
Papillary Ca
Anaplastic Ca
Follicular Ca
Thyroid and Parathyroid