Immunohistochemical analysis of pituitary adenomas in a West African hospital

Abstract

Purpose: Pituitary adenomas are the commonest tumors of the sellar region and constitute 10% to 15% of intracranial neoplasms. The conventional classification of pituitary adenomas is according to the hormone expression of the tumors as determined by immunohistochemical methods. There is paucity of existing research on the frequencies of the various immunohistochemical types in our environment. The purpose of this retrospective study was to determine the relative frequency of specific pituitary adenoma subtypes seen at our hospital over a period of twelve years.

Methods: Forty seven pituitary adenomas received over the study period satisfied the inclusion criteria and their paraffin blocks were retrieved from the archives of the department of Pathology, University College Hospital, Ibadan. Tissue sections were stained with antibodies for Prolactin, Growth hormone, ACTH, TSH, FSH and LH using the streptavidin-biotin-peroxidase method. The tumors were classified using the 2004 WHO classification of pituitary adenomas. Results were tabulated and analyzed using the SPSS statistical software package.

Results: Most adenomas presented between the fourth and seventh decades with a slight female preponderance. Gonadotroph and null cell adenomas were commonest and each constituted 34%, followed by prolactinomas, which accounted for 14.9% of the tumors. There were no thyrotroph adenomas.

Conclusion: The lower incidence of prolactinomas in this study may be due to the use of other therapeutic modes rather than surgical treatment but may also indicate racial differences. However there is a need for further characterization of the null cell adenomas using ultrastructural and molecular studies.

Keywords: Pituitary, Adenoma, Classification, Immunohistochemistry, Endocrine