[Space occupying processes of the sellar region with emphasis on tumor-like lesions]

Most space occupying lesions of the sellar region are tumors (e.g., pituitary adenomas, craniopharyngiomas, but also meningiomas). In approximately 8% of patients with sellar mass lesions, non-neoplastic disorders (e.g., inflammations, cysts, hyperplasia) are causal. Cystic lesions of the pituitary region are classified as Rathke's cysts, colloid cysts, arachnoidal cysts and epidermoid cysts. These have to be differentiated from cystic craniopharyngeomas or cystic pituitary adenomas. Autochthonous inflammations (lymphocyctic hypophysitis, idiopathic granulomatous hypophysitis, xanthomatous and peritumorous hypophysitis) have to be distinguished from generalized diseases involving the pituitary (e.g., sarcoidosis, tuberculosis). Hyperplasia can result in a doubling of pituitary size. Lactotroph and corticotroph hyperplasia are the most common and may be of a diffuse and nodular type. The nodular form of pituitary hyperplasia may show transition into adenoma. Other hyperplasias may be found adjacent to adenomas or other tumours. Furthermore, vascular (aneurysms) and bony lesions (especially fibrous dysplasia) can appear as space occupying lesions of the sellar region.