ABSTRACT
Background and Purpose: Pituitary adenomas without clinically active hypertension are termed as non-functioning adenoma [NFPA]. These tumors represent about one quarter of all pituitary tumors. Immunohistochemical methods are the gold standard methods of identifying them. The Ki-67 is a nuclear antigen detected by the monoclonal antibody MIB-1, whose labeling index [LI] is considered as a marker of normal and abnormal cell proliferation
Methods and Materials: In this clinicopathological study, 85 cases of NFPAs were analyzed immunohistochemically
Results: MIB-1 LI was measured in all surgical specimens, which was higher than 5% only in 5 cases. Also, 18 cases were immunoactive to one or two adenohypophysial hormones
Conclusion: NFPAs comprise several pathologically different types of tumors, some of which are potentially hormone producing tumors. However, probable defects in hormone secretion may be the cause of not increasing the adenohypophysial hormone levels in the serum and consequent syndromes