**2.2 Pituitary adenomas**

Pituitary adenomas are one of the most common intracranial tumors and are associated with a high rate of morbidity and mortality [25]. The prevalence of pituitary adenomas is approximately 100 per 100.000 [26–28]. Radical tumor

resection is indicated, with a transsphenoidal approach [29]. Adenomas that secrete hormones are called functioning adenomas, and adenomas that do not secrete hormones are called nonfunctioning adenomas [28]. Nonfunctioning

**Figure 3.** *MRI scan with Gd of a large left-sided sphenoid wing meningioma.*

#### **Figure 4.**

*Stereotactic radiation therapy dose plan in BrainLab/iPlan, of a right cavernous sinus meningioma, with isodose lines, demonstrating collateral irradiation of the optic chiasm, pituitary gland, and vascular structures of the cavernous sinus and circle of Willis***.**

#### **Figure 5.** *MRI scan with Gd of a right petroclival meningioma.*

**Figure 6.** *MRI sagittal T1 with Gd of a pituitary microadenoma.*

and prolactin-secreting adenomas are the most common types of pituitary adenomas, followed by growth hormone secreting and corticotroph adenomas, thyrotropin, and gonadotropin secretin) g adenomas [26, 28, 29]. Macroadenomas, which are defined as tumors with a diameter > 10 mm, are more common than microadenomas, which are <10 mm in diameter [28, 29]. The first-line treatment of prolactinomas is medical, with a dopamine agonist (**Figure 6**) [28].

Nonfunctioning pituitary adenomas are often large at presentation and are usually diagnosed due to their mass effect, visual loss, and hypopituitarism [27, 28]. Occasionally, they may constitute an asymptomatic incidental finding. They may also cause hyperprolactinemia due to pressure on the pituitary stalk. The main indication for surgery is reversal of visual loss, and in many cases, it may reverse hypopituitarism [29]. When surgical treatment does not provide sufficient disease control or has serious side effects, such as visual loss, then stereotactic radiosurgery or fractionated stereotactic radiation therapy is indicated, and in some instances, this may then be the sole treatment of the tumor (**Figure 7**). Also, stereotactic irradiation may be effective when surgery has failed to restore biochemical control in hormone-secreting adenomas [7].

*Stereotactic Radiotherapy for Benign Skull Base Tumors DOI: http://dx.doi.org/10.5772/intechopen.102468*

**Figure 7.** *FSRT dose plan of a large pituitary macroadenoma.*
