Pathology of pituitary tumors

This article reviewed the classification, morphologic features, and pathogenesis of human hypophyseal adenomas and differences between hyperplasia and adenoma. Histologic, immunohistochemical, and electron microscopic investigation obtained a deeper insight into several aspects of pituitary cytopathology. Based on these studies, a meaningful classification has been developed that separates hypophyseal adenomas into distinct entities. It hinges on histology, hormone content, ultrastructural characteristics, cellular composition, and cytogenesis and correlates the morphologic features of adenoma cells with endocrine activity. Although progress has been spectacular during the last two decades in the better understanding of structural characteristics and hormonal function of pituitary adenomas, much more work is necessary to shed light on structure-function correlations and pathogenesis. Collaborative investigations between clinical investigators and basic scientists can further advance knowledge in this intriguing and important field.