Histopathological classification of pituitary adenomas and prognostic significance of ki 67 labeling i?ndex

It is difficult to evaulate the recurrence and progression potential of pituitary adenomas at presentation. The WHO Organization classification of endocrine tumors suggests that invasion of the surrounding structures, size at presentation, an elevated mitotic index, a Ki 67 labeling index higher than %3 and extensive p53 expression are indicators of aggressive behavior. [1, 48, 107] Ki 67, a marker of cellular proliferation, has been studied extensively in pituitary neoplasia. It is of relevance to various clinicopathological parameters, including tumor subtype, size, invasiveness and recurrence, as well as hormonally activity. Generally, pituitary tumors behaving agressively have increased Ki 67 labeling indices. [111] In our study, 303 cases which had been diagnosed as pituitary adenoma between 2006-2013 years at the Pathology Department of Gazi University Medical Faculty were examined. The World Health Organization (WHO) 2004 classification of endocrine tumors proposed that Ki 67 proliferation index, which means that the diagnostic and prognostic, investigated the relationship between prognosis, histopathological subtypes and clinicopathological parameters mentioned above in literature. In the end of the study, a significant association of Ki 67 labeling index with radiological invasiveness surrounding structures and recurrence was found in pituitary adenomas (p=0,030 p=0,007) Statistically significant correlation was found in radiological invasion and mitosis. (p=0,011) Although not detected in significant association between the subtypes of pituitary adenomas and Ki 67 labeling index (p=0,289), significant differance was found between the subtypes and radiological invasion and recurrence. (p=0,011 ve p=0,0001) Consequently, as well as the radiological invasion is an important parameter which indicates recurrence, in histological evaluated, pituitary tumor subtyping and Ki 67 labeling index are the other important parameters that determining the biological behavior of the adenoma. Key words: Pituitary adenoma, Ki 67, immunohistochemistry.