Pituitary adenomas are commonly occurring, benign neoplasms that account for 15% of intracranial neoplasms but their pathogenesis remains elusive. To explore the possible pathogenesis of pituitary adenomas, we used fiber-optic bead arrays to compare the gene expression profiles in five major pituitary adenoma subtypes to normal pituitary gland from three recently deceased males. We used reverse transcriptase real time quantitative polymerase chain reaction (RT - qPCR) to randomly validate the expression of four differentially expressed genes in the five pituitary adenoma subtypes and three normal pituitary glands. We then analyzed the profiles of the differentially expressed genes using the Kyoto Encyclopedia of Genes and Genomes pathways. Array analysis showed that 129 genes and two expressed sequence tags were differentially co-expressed in all pituitary adenomas. Pathway analyses showed that the extracellular matrix-receptor interaction pathway and the transforming growth factor-beta signaling pathway may have an important role in tumorigenesis of the five pituitary adenoma subtypes. Thus, we suggest the presence of a common mode of pathogenesis in pituitary adenoma subtypes. Fiber-optic bead array analysis combined with pathway analysis of differentially expressed genes appears to be a valid method of investigating the pathogenesis of different tumors. (C) 2011 Elsevier Ltd. All rights reserved.