Tumors of the Pituitary Gland

Anterior pituitary tumors are clonal proliferation of pituitary cells. They usually consist of one cell type, although some adenomas consist of more than one cell type. Pituitary tumors can be characterized by broad spectrum markers such as synaptophysin and chromogranin. Reticulin histochemical staining is useful in separating normal hyperplastic and neoplastic pituitary tissues. Electron microscopy is a powerful tool to help separate various subtypes of adenomas including sparsely and densely granulated growth hormone adenomas and different subtypes of silent ACTH adenomas. The major types of pituitary adenomas include GH, PRL, ACTH, TSH, gonadotroph (FSH/LH), and null cell adenomas. A combination of hematoxylin and eosin staining, immunohistochemistry, and electron microscopic studies are the most comprehensive ways of classifying pituitary tumors.