Study of parathyroid transcription factor Gcm2 expression in parathyroid lesions

Glial cells missing 2 (Gcm2) is a master regulatory gene of parathyroid gland development, and it is exclusively expressed in the parathyroid gland. Diagnostic application of anti-Gcm2 antibody has not been reported yet. In this study, a total of 58 cases of parathyroid lesions including 40 adenomas, 2 atypical adenomas, 2 carcinomas, 9 hyperplastic lesions, 4 parathyroid cysts, and 1 case of recurrent hyperplasia of an autograft gland were stained with anti-Gcm2 antibody. Anti-Gcm2 was also applied to a variety of endocrine tumors, including thyroid tumors and nonendocrine tumors, and normal tissues from a variety of organs, including the parathyroid and thyroid glands. Gcm2 nuclear expression was seen in all the normal parathyroid glands, and cystic, hyperplastic, and neoplastic parathyroid lesions in a diffuse manner, whereas no Gcm2 expression was seen in any other normal tissues and tumors, including those of the thymus and thyroid gland. Anti-Gcm2 antibody is a highly sensitive and specific marker for parathyroid lesions. Although the immunohistochemistry stain for parathyroid hormone is a useful marker, its reaction tends to be variable in extent and intensity in parathyroid neoplasia, and it is often negative in parathyroid cysts, and Gcm2 would serve as a useful adjunct marker.