[579] A Study of Parathyroid Transcription Factor GCM2 Expression in Parathyroid Lesions

D Nonaka. New York University School of Medicine, New York, NY

Background: The parathyroid glands and thymus arise from a common primordium of the third and fourth pharyngeal pouch endoderm. The expression of the transcription factors Gcm2 and Foxn1 divides the primordium into parathyroid- and thymus-specific domains. Gcm2 is exclusively expressed in the parathyroid gland in humans, and deletion of this gene in mice results in absence of the parathyroid glands. There is no study on Gcm2 immunohistochemistry application in surgical pathology.
Design: A total of 40 cases of parathyroid lesions including 27 adenomas, 2 atypical adenomas, 2 carcinomas, 8 hyperplastic lesions, and 1 case of recurrent hyperplasia of autograft gland were stained with anti-Gcm2 antibody. Anti-Gcm2 was also applied to 70 thyroid tumors (follicular adenoma/carcinoma including Hürthle cell type, and papillary, insular, medullary and anaplastic carcinomas), 27 adrenocortical tumors (adenomas and carcinomas), 43 pheochromocytomas and paragangliomas, 32 carcinoids from the lung and GI tract, and 28 Merkel cell carcinomas, 116 pulmonary adenocarcinomas, 29 pulmonary squamous cell carcinomas, 50 carcinomas from a variety of organs, and 34 melanomas as well as tissues from a variety of organs including parathyroid. The extent of staining was graded as focal (5-50%) and diffuse (50-100%).
Results: Gcm2 nuclear expression was seen in all normal, hyperplastic and neoplastic parathyroid lesions in diffuse fashion while no Gcm2 expression was seen in any other normal tissues and tumors including thymus and thyroid.
Conclusions: Parathyroid transcription factor, Gcm2, is a highly sensitive and specific marker for parathyroid lesions. Although parathyroid hormone (PTH) immunohistochemistry stain is a useful marker, its reaction tends to be variable in extent and intensity in parathyroid neoplasia, and Gcm2 would serve as a useful adjunct marker.
Category: Endocrine

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 32, Tuesday Afternoon


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