Immunohistochemical Patterns of Pituitary Adenomas in Southeastern Nigeria, a 10-year Histopathologic Review

Introduction: Pituitary adenomas [PAs] constitute the third most common primary intracranial tumours, with a wide prevalence rate of 1% to 40%. Histologic (H & E) classification into acidophilic, basophilic and chromophobic adenomas have little clinical relevance but WHO recommended immunohistochemical subclassification has both therapeutic and prognostic significance. This immunohistochemical subclassification has not been done in our environment, making it imperative for us to evaluate the patterns in our environment.Aim: To determine the immunohistochemical patterns of PAs in Southeastern Nigeria.Materials and Methods: This was a 10-year retrospective review of all PA biopsies received at University of Nigeria Teaching Hospital Enugu, Memphys Hospital for Neurosurgery Enugu and Grace Pathology Consults Enugu, Nigeria. The age, sex, histologic, immunohistochemical subtypes and biopsy size of all diagnosed PAs were analyzed using Statistical Package for Social Sciences (SPSS) version 20 (New York: IBM Inc.) and the results were expressed in descriptive statistics.Results: One hundred cases of PAs were identified in this study constituting 19.6% of all primary intracranial tumors received at our study centers during the period under review. There were 45 (45.0%) females and 55 (55.0%) males giving a female to male ratio of 1:1.2, and a mean age of 45.3 years. The commonest histologic type was acidophilic adenoma (49.0%), followed by basophilic (40.0%) and chromophobic (11.0%) adenomas. Null cell adenomas were the most common immunohistochemical subtype (44.0%), followed by PRL-secreting adenomas (27.0%). Others were Luteinizing hormone (LH) - 13 (13.0%), follicle stimulating hormone (FSH) - 7 (7.0%), growth hormone (GH) - 3(3.0%), TSH - 2(2.0%) and ACTH - 1(1.0%) adenomas.Conclusion: PAs predominate amongst males, occurring mostly in the middle age groups in Southeastern Nigeria. Null cell adenoma is the commonest immunohistochemical subtype followed by PRL-secreting adenomas. Routine immunohistochemical characterization is required for accurate diagnosis and optimal patient care.