Pituitary tumors are a group of neoplasms originating from the anterior and posterior lobes of the pituitary gland, as well as from remnants of craniopharyngeal epithelial cells. Clinically, they account for about 10% of all intracranial tumors, with the vast majority being benign. They occur slightly more frequently in males than in females and are most commonly diagnosed in young and middle-aged adults. The typical clinical manifestations are as follows:
Hormonal Secretion Abnormalities
Tumors affecting hormone secretion are common, with prolactinomas accounting for more than half of all pituitary adenomas. These lead to hyperprolactinemia, which causes symptoms such as abnormal lactation. Excessive secretion of growth hormone can cause acromegaly. When normal pituitary tissue is compressed, symptoms of decreased hormonal production may occur, such as hypogonadism resulting in amenorrhea, infertility, or erectile dysfunction. Decreased secretion of thyroid-stimulating hormone (TSH) may result in symptoms such as dry skin and myxedema, while reduced adrenocorticotropic hormone (ACTH) levels can lead to general fatigue, loss of appetite, and weight loss.
Symptoms Due to Tumor Compression of Surrounding Structures
Signs of Nerve Fiber Irritation
Direct stimulation by the tumor or increased intrasellar pressure as the tumor grows can lead to headaches. Approximately two-thirds of patients experience headaches in the early stages, which are typically localized behind the orbits, in the forehead, or in both temporal regions. The headaches are usually mild and intermittent. If the tumor grows upward and breaches the diaphragm of the sella, the intrasellar pressure may decrease, potentially alleviating or resolving the headache. However, as tumor growth progresses, headache symptoms may reappear.
Compression of the Optic Nerve, Optic Chiasm, and Optic Tract
The most common growth direction of the tumor is upward, compressing the optic chiasm and optic nerve. This results in visual impairment, including decreased visual acuity and unilateral or bilateral temporal hemianopia.
Invasion of Adjacent Structures
The tumor may invade laterally into the cavernous sinus, affecting the oculomotor nerve, trochlear nerve, abducens nerve, and trigeminal nerve. This can cause ptosis, impaired eye movement, and trigeminal neuralgia. It may also compress the cerebral peduncle or cerebral hemispheres. Pituitary apoplexy may lead to a decline or loss of pituitary function and can cause subarachnoid hemorrhage or intracerebral hemorrhage.
Systematic evaluation of pituitary tumors is required. This includes assessments of endocrine hormones, contrast-enhanced MRI and CT imaging, examinations of major blood vessels, and tests of visual acuity and visual fields. Consideration of the patient's symptoms and response to medical therapy is necessary to determine whether surgery is needed and to select the appropriate surgical approach. Most pituitary tumors can be removed endoscopically via a transnasal route, although a small number of cases may require combined transcranial and endoscopic transnasal surgery. Additional treatment options include radiotherapy (e.g., Gamma Knife technology). Medical therapy, particularly bromocriptine, is effective in inhibiting prolactin secretion and reducing growth hormone levels in patients with acromegaly.