How to Differentiate Between Pituitary Hyperplasia and Adenoma

Clinically, hyperplasia can be indistinguishable from adenoma using standard H&E staining. In order to make a diagnosis, one must use reticulin stain. Pituitary cells are surrounded by architecture of reticulin fibers and when the cells undergo hyperplasia, the reticulin architecture s maintained. In adenoma, the reticulin fiber architecture is disrupted. 

 Intact reticulin fiber from pituitary hyperplasia

 Disrupted reticulin fiber from pituitary adenoma