Abstract

The development of immuohistochemistry and the application of electron microscopy have revolutionized our understanding of the pathopysiology of pituitart adenoma. The clinical value of functional characterization of pituitary adenoma has been realized. Immunohistochemical stains using polyclonal antibodies to six pituitary hormones (GH, PRL, ACTH, TSH, FSH & LH) were performed to classify the pituitary adenoma and to investigate the relationship between the results of the immunohistochemical study and pared to the serum hormone level. The results are summarized as follows: The Most common clinical type of pituitary adenoma was prolactinoma and the second was nonfunctioning adenoma. However, the most common immunohistological type of pituitary adenoma was null cell adenoma, the second one, lactotrope adenoma and the third one, mixed sommatotrope & lactotrope adenoma. In the clinically nonfunctioning adenoma cases, null cell adenoma were present in 75%; gonadotrope adenoma and corticotrope adenoma were present in 25%, while the serum prolactin level was increased in ten of the twenty cases(50%) of the null cell adenoma. When the serum prolactin level was increased above the 150ng/ml, the tumor cells gave positive reactions in 95.2% of cases immunohistochemically. But in the cases of GH, FSH & LH, the tumor cells gave positive reactions in 100%, 75%, and 66.7%, respectively. In the case of increased serum prolactin level, more than 50% and 30% proportion of tumor cells showed positive reactions in the micro- and macroadenoma, respectively.

• Keywords: Pituitary adenoma;Immunohistochemistry