[Classification, pathology and molecular biology of pituitary adenoma].

Pituitary adenomas were once considered a homogenous collection of morphologic entities distinguishable pathologically by differences in cytoplasmic staining affinities. Methodological and conceptual advances over the past decade have since confirmed the contrary demonstrating that pituitary adenomas are morphologically and biologically diverse, and that designations such as acidophilic, basophilic and chromophobic, beyond their descriptive merit, are without consistent morphologic, endocrinologic or practical significance. The application of electron microscopy and immunohistochemistry has brought forth a new classification of pituitary adenomas based on ultrastructure and hormonal content, updating understanding of their pathology, secretory function and cytogenesis. As a primary objective, current functional classification of pituitary tumors is discussed in detail. In addition to reviewing the morphology of pituitary tumors, special emphasis is also placed on the important clinicopathologic correlations relevant to these lesions.