C	C6432	Multiple Endocrine Neoplasia	Multiple Endocrine Neoplasia Syndrome(s)	MEN Syndromes	An autosomal dominant inherited neoplastic syndrome characterized by the development of various endocrine neoplasms and abnormalities in various anatomic sites. There are four types recognized: type 1 (MEN 1), caused by inactivation of the tumor suppressor gene MEN-1, type 2A (MEN 2A), caused by mutation of the RET gene, type 2B (MEN 2B) also caused by mutation of the RET gene, and type 4 (MEN 4) caused by mutation of the CDKN1B gene. Patients with MEN 1 may develop hyperparathyroidism and parathyroid gland adenomas, pituitary gland adenomas, pancreatic islet cell neoplasms, and carcinoid tumors. Patients with MEN 2A develop medullary thyroid carcinomas and may also develop pheochromocytomas and parathyroid gland hyperplasia. Patients with MEN 2B develop medullary thyroid carcinomas and numerous neural defects including neuromas. Patients with MEN 4 develop endocrine neoplasms, particularly in the parathyroid glands, pituitary, and pancreas.	A genetically heterogenous group of autosomal dominant neoplastic syndromes characterized by the development of neoplasms in various endocrine organs.	C3010	Endocrine Neoplasm			C118467	Pediatric Endocrine Terminology	
C	C3878	Thyroid Gland Anaplastic Carcinoma	Anaplastic Thyroid Carcinoma	Undifferentiated Thyroid Tumor	A primary carcinoma of the thyroid gland composed of undifferentiated cells.  The malignant cells demonstrate evidence of epithelial differentiation, either by immunohistochemistry or electron microscopic studies. Microscopically, in the majority of cases there is a mixture of spindle, epithelioid, and giant cells. The vast majority of the patients present with a rapidly enlarging neck mass. The clinical course is usually aggressive.	An aggressive carcinoma of the thyroid gland composed of undifferentiated cells.	C3414	Thyroid Tumor			C118467	Pediatric Endocrine Terminology