2 - Immunohistochemistry and Electron Microscopy as Evaluation Criteria in Tumor Classification in the Deciphering of Pituitary Adenomas

Abstract

This chapter introduces immunohistochemistry and electron microscopy (EM) as evaluation criteria in tumor classification in the deciphering of pituitary adenomas. The chapter also presents a pathology classification of pituitary adenomas. Pituitary adenomas are benign neoplasms originating in adenohypophyseal cells representing 15% of all intracranial tumors, which express a wide hormonal and proliferation behavior. Pituitary adenomas with normal plasma hormone levels do not always correspond with pathology. When pituitary adenomas are hormonally inactive, they are not clinically detected and are discovered only incidentally (by CT/MRI scanning). Due to modern methods of cellular study (such as immunohistochemistry, EM, and in situ hybridization), tinctorial classification is of no use because of the failure to bring information about hormone content and biological activity of the tumor cells. For correlation between hormone production, secretory activity and cytogenesis, immunohistochemistry, and transmission, EM investigation is needed.