What Is a Pituitary Adenoma?
The pituitary gland is a small but important organ located at the base of the brain that regulates many of the body’s hormonal functions. Pituitary adenomas, which arise from this gland, are mostly benign tumors; however, benign does not necessarily mean insignificant.
Some adenomas secrete excessive amounts of hormone and cause hormonal disorders, while others secrete no hormone and, as they grow over time, may cause compression of the surrounding tissues, particularly the optic chiasm, where the optic nerves cross.
For this reason, not every patient diagnosed with a pituitary adenoma necessarily needs surgery. The treatment decision is made by evaluating together the type and size of the tumor, its hormonal activity, its effect on the visual pathways, its tendency to grow and the patient’s clinical characteristics.
What Are the Symptoms of Pituitary Adenomas?
Symptoms may vary according to whether the adenoma secretes hormone and according to its size.
Possible complaints include:
- Headache
- Narrowing of the visual field or reduced vision
- Menstrual irregularity
- Milk discharge from the breast
- Changes in sexual desire or reproductive function
- Coarsening of the features of the hands, feet or face
- Excessive thirst and frequent urination
- Weight gain, red/purple stretch marks on the abdomen
- Fatigue and symptoms of hormone deficiency
For this reason, a treatment decision is not made by looking at the MRI image alone. Hormone tests, ophthalmological and visual field assessment, and pituitary MRI should be evaluated together.
Is Every Pituitary Adenoma Operated On?
No.
In some adenomas, particularly those found incidentally that are small, secrete no hormone and cause no compression of the visual pathways, regular MRI and hormone checks may be sufficient. In patients who do not require surgery, follow-up is planned according to the size and clinical characteristics of the tumor.
By contrast, surgical treatment may come into consideration for adenomas that result in loss of vision or visual field defects, cause significant compression of the optic chiasm or lead to certain hormonal diseases.
Which Pituitary Adenomas Require Surgery?
Although the decision for surgery is individual, it is considered particularly in the following situations:
If There Is Compression of the Optic Nerves
Large adenomas may grow upwards and cause compression of the optic chiasm. The development of visual field loss or progressive visual impairment is an important finding with regard to surgical assessment.
If the Adenoma Secretes Hormone
In some adenomas that secrete excessive amounts of hormones such as growth hormone or ACTH, surgical treatment may be an important option. For example, in ACTH-secreting adenomas that cause Cushing’s disease, transsphenoidal surgery is one of the main treatment options in suitable patients.
There is, however, an important exception: in prolactin-secreting adenomas, known as prolactinomas, the first treatment in most patients is medication. Dopamine agonists such as cabergoline in particular can lower the prolactin level and shrink the tumor. Surgery may come into consideration in selected patients in whom drug treatment is ineffective or not tolerated.
How Is Endoscopic Pituitary Surgery Performed?
One of the methods frequently used today in the surgical treatment of pituitary adenomas is endoscopic endonasal transsphenoidal surgery.
In this method, the surgeon advances through the nose and reaches the region of the pituitary gland via the sphenoid sinus behind the nose. The aim is thus to reach the tumor without making a large incision over the upper part of the skull.
The endoscope can give the surgeon views of the operative field from different angles. Surgical planning takes into account in particular the anatomical features of the pituitary region and the relationship of the tumor to the surrounding structures.
Endoscopic surgery does not, however, automatically mean the “most suitable” method for every patient. The surgical approach is determined by evaluating the size and extension of the tumor, its relationship to the surrounding structures and the aim of the surgery.
What Happens After Surgery?
After surgery it is important to assess hormone levels and, in particular, pituitary function. Visual function and follow-up MRIs are also part of the follow-up process.
In some adenomas it may not be possible to remove the whole tumor. Particularly in tumors that spread into the surrounding structures or extend into critical regions such as the cavernous sinus, residual tumor tissue does not always mean an unsuccessful operation. Depending on the patient’s condition, observation, a second operation, radiation therapy or medical treatment options may be considered.
Frequently Asked Questions
Is a pituitary adenoma cancer?
The great majority of pituitary adenomas are benign tumors. They may, however, lead to significant clinical problems through hormone production or compression of the surrounding structures.
Should every pituitary adenoma be operated on?
No. Some small adenomas that secrete no hormone and cause no compression of the visual pathways can be followed regularly. Whether surgery is needed is determined by the patient’s clinical and radiological findings.
If the prolactin level is high, is surgery always necessary?
No. In a large proportion of patients diagnosed with a prolactinoma, the first treatment is medication. Surgery may come into consideration in cases of resistance to drug treatment, serious side effects or certain clinical situations.
Is pituitary surgery performed through the nose?
In suitable patients, the pituitary gland can be reached through the nose by endoscopic endonasal transsphenoidal surgery. The surgical approach is, however, determined by the characteristics of the tumor.
Conclusion
A diagnosis of pituitary adenoma does not in itself mean that surgery is necessary. Some adenomas require only regular follow-up, while others can be controlled with medication. In adenomas that cause compression of the visual pathways or secrete certain hormones excessively, surgery may be an important treatment option.
In particular, the treatment approaches to prolactinoma, growth hormone-secreting adenoma and ACTH-secreting adenoma differ from one another. For this reason, the right treatment decision in pituitary adenomas should be based on a multidisciplinary evaluation by neurosurgery, endocrinology, radiology and, when necessary, ophthalmology specialists.
For more information on the diagnosis, treatment options and surgical management of brain tumors, please visit the Brain Tumors page.
References
- Lillehei KO, Travers S, Barkhoudarian G, et al. Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines for the Role of Surgery for Patients With Functioning Pituitary Adenomas. Neurosurgery. 2025;97(3S):S24-S35.
- Petersenn S, Fleseriu M, Casanueva FF, et al. Diagnosis and management of prolactin-secreting pituitary adenomas: a Pituitary Society international Consensus Statement. Nature Reviews Endocrinology. 2023;19:722-740.
- Freda PU, Beckers AM, Katznelson L, et al. Pituitary Incidentaloma: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism. 2011.
- Kuo JS, Barkhoudarian G, Farrell CJ, et al. Congress of Neurological Surgeons Systematic Review and Evidence-Based Guideline on Surgical Techniques and Technologies for the Management of Patients With Nonfunctioning Pituitary Adenomas. Neurosurgery. 2016;79(4):E536-E538.