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PITUITARY TUMOR

Pituitary Tumors constitute approximately fifteen (15 %) percent of all Brain Tumors. The Pituitary Gland lies underneath the Brain within a protective bone structure called the "Sella Turcica" (so named because early anatomists believed that it looked like a "Turkish Saddle".) The Pituitary Gland is commonly referred to as the "Master Gland" of the body, because of its central role in making and controlling hormones, which themselves influence the functioning of the other hormone producing glands which make up the "Endocrine" system of our bodies. The Pituitary Gland has several anatomical parts, including an Anterior (front) Lobe, a Posterior (rear) Lobe, as well as, an Intermediate portion and a "Stalk", which connects the Pituitary Gland to the overlying Brain structure, called the "Hypothalamus". As in other instances in life, when one believes that they are the "Master" there is usually a "Higher Authority". In this case the Hypothalamus is the "Higher Authority" to the Pituitary Gland.

The Neurosurgical Consultants' staff have a long standing and specific interest in Pituitary Tumors. We have prepared a rather comprehensive review of the entire subject of Pituitary Tumors and urge you to consider taking time to consult that reference which is available in the Downloads & Information section this website.

In addition, there are many websites devoted to the Pituitary Gland and Pituitary Tumors. Some of these are reliable, while some are misleading. We can recommend, as an adjunct, the website of The Pituitary Network Association as a reliable primary resource.

SYMPTOMS

The Symptoms that a patient will manifest depend on the type of cell making up the tumor, the degree of local "invasion" of the Skull Base (by aggressive tumor varieties) and the size of the tumor.

Some small tumors can create serious clinical problems, because they secrete excessive amounts of hormones, which then cause deleterious effects. Examples of such diseases resulting from the hyper-secretion of hormones that frequently occur in patients harboring very small tumors are: Cushing's (resulting from an overproduction of ACTH which causes the Adrenal Glands to massively over produce steroids); Acromegaly or Gigantism (resulting from an overproduction of Growth Stimulating Hormone) and Hypersecretion of Prolactin (Prolactin overproduction results in breast milk production even in male patients as well as other hormone abnormalities).

Figure 1: MRI Scan (Gadolinium Enhanced Transaxial View) of a Giant "Null Cell" Pituitary Tumor (Arrow).

This patient had progressive visual loss over several years as well as lethargy and personality change.



Figure 2A (Left): MRI Scan of a Growth Hormone (GH) Pituitary Tumor confined to the Sella Turcica. This patient is an excellent candidate for Minimally Invasive Microendoscopic Transsphenoidal removal.

Figure 2B (Right): Acromegalic patient. Photo taken 24 hours post-operative Minimally Invasive Microendoscopic DIRECTED Transsphenoidal Resection of a Growth Hormone producing Pituitary Tumor.

Another tumor that over produces the hormone PROLACTIN, can cause women to stop their menstrual cycle, produce breast milk and be unable to conceive a child. In men, this Prolactin secreting tumor can cause their breasts to grow, and produce milk, while also inducing testicular atrophy and impotence. Once again the tumors can vary from quite small, to very large.

The majority of Pituitary Gland tumors arise from cells that do not produce any hormones. This is known as the "NULL CELL" tumors, which tend to become quite large (see Figure 1) and grow beyond the confines of the bone of the Sella Turcica. These large tumors often compress the visual sensory apparatus (Optic Nerves and Optic Chiasm), resulting in impaired vision or blindness. Patients are often not aware of the subtle early changes of visual impairment and only become aware of the change in vision when they either cannot see out of one eye, or their peripheral vision has deteriorated. As the tumor grows above the Sella Turcica, it stretches the Optic Nerves, as well as the blood supply to the nerves and the Optic Chiasm thus progressively impairing their function. Tumors that "hypersecrete" can also grow to prodigious size. An example of such a Prolactin hypersecreting tumor is presented in Figures 3A & B.)

Pituitary Tumors are almost always benign although there is a small percentage that can be malignant. Nevertheless, even some benign tumors can be very aggressive, resulting in local invasion. This can present quite a management challenge such as when the tumor invades the Cavernous Sinus (an anatomical structure lying beside the Sella Turcica where the Carotid Arteries and Cranial Nerves 3/4/5 & 6 exist. (See Figures 1 & 3)

The diagnosis of a Pituitary Tumor is usually made with MRI or CT scanning. Endocrinological evaluation is an integral part of the investigation of these patients.

TREATMENT

There are options for treatment which include "masterful inactivity and cat-like observation" (also known as "do nothing"), hormonal therapy, surgery and radiation therapy. "Observation" is appropriate for some small tumors, including some Prolactin secreting tumors in young women, who do not wish to become pregnant. Follow-up evaluations, including Endocrinological management and MRI scanning, is mandatory for patients who choose this option.

Medical

For hormonally active tumors, endocrinologists often prefer to treat patients for extended periods of time with medications. While this remains a contentious area between the disciplines of Endocrinology and Neurosurgery, there is credible scientific and clinical evidence to consider medical management in some patients. There are times when a surgeon would prefer to see the tumor reduced in size by medication prior to removing it. In other instances, the patient may be a very poor surgical candidate by virtue of intercurrent diseases. Many patients, who initially try the medications, find the side effects intolerable and strongly prefer surgical management.

The case illustrated in Figures 3A & B is one of a 33 year old male referred from a Neuro-ophthalmologist with severe visual impairment. His Prolactin level was 10,761 (normal range is 3.0-30.0). Other aspects of his Pituitary function were impaired as well including Steroid production (Serum Cortisol >2/ Luteinizing Hormone 0.7/Testosterone 10/Somatomedin-C 45.4.) The Endocrinological consultant made an excellent case for attempting "agonist" therapy (medications that act against the production of Prolactin) as a primary form of management. This treatment plan consists of high dose "agonist" medication for 4 weeks after which follow up blood Prolactin levels, MRI scan and a visual field examination are carried out. In the event that there is worsening of the visual field or no significant improvement, surgical intervention becomes appropriate. Long-term medication is required in those cases which do respond to this medical regimen as this patient has.


Figure 3A (Left): MRI Scan (Gadolinium Enhanced Sagittal View) Very large Prolactin secreting tumor (Curved Arrow) in a 37 year old male invades the Skull Base.

Figure 3B (Right): MRI Scan (Gadolinium Enhanced Coronal View) of the same patient as 3A. This locally aggressive Tumor invades both Cavernous Sinuses (Curved arrow indicates the invasion of the right Cavernous Sinus) and extends through the "floor" of the Right Middle Cranial Fossa (Horizontal Arrow).


Surgery

The choice of surgical approach in the management of Pituitary Tumors primarily relates to their size, configuration, tissue density, degree of local "invasion", the skill level and experience of the Neurosurgeon. A standard surgical approach utilizes Transsphenoidal Microneurosurgical techniques. While most Pituitary tumors can be managed this way, there are some technical limitations. A Craniotomy (opening of the skull) approach is occasionally required particularly for giant tumors or those with a dense surrounding capsule and/or dense fibrous tissue component. Transsphenoidal Surgery is the mainstay operation for these tumors. This approach is through a small opening in the nose. For those Neurosurgeons with a large experience (over 500 cases), this commonly allows for a complete surgical removal of the tumor. In most instances, the Pituitary Gland and its function can be entirely preserved.

Minimally Invasive Microendoscopic Transsphenoidal Techniques are also available for some of these tumors. These techniques are accomplished using a modified Transsphenoidal avenue. These procedures are available in some institutions as demonstrated in the accompanying photos from our practice. This approach also has some limitations, nevertheless it is highly recommended for many tumors. There are rare circumstances when simultaneous Transsphenoidal and Craniotomy approaches are require. Many of these involve the specialists who make up the Skull Base Tumor Team.


Radiation Therapy

In the past, radiation therapy for Pituitary Tumors was associated with some serious risk of damage to the visual sensory apparatus as well as the Temporal Lobes. Modern radiation therapy, particularly Stereotactic Radiosurgery, has made these complications less likely.

Radiation Therapy of any variety is rarely appropriate as an initial form of treatment, since one would not wish to treat a tumor without having biopsy confirmation of the cell type. In addition, it is inappropriate to radiate in cases where the tumor is exerting significant pressure upon, and displacing, the visual sensory apparatus. Radiation Therapy to a large tumor, without prior decompression, runs the serious risk of causing the tumor and the visual sensory apparatus to swell, with the attendant consequence of blindness.

Radiation therapy can be very effective in controlling the residual tumor in cases of non-secreting tumors, in cases of locally aggressive, invasive tumors in cases of malignant tumors. There are also indications to use Radiation Therapy in selected cases of hormone secreting tumors, where Medical Therapy is failing or poorly tolerated.

Follow-up

In all cases, long term follow up is important. This includes yearly MRI scans for most of these patients particularly for those where incomplete resection was carried out.

Chemotherapy

Chemotherapy in the form of traditional and exotic agents is generally unwarranted. Hormonal therapy is commonly utilized for many patients, either alone, or in combination with surgery.

Neurosurgical Consultants' Experience

The Neurosurgical Consultants' staff has a long standing and specific interest in Pituitary Tumors. Dr. Lazar has operated on over 500 Pituitary Tumor patients and has long term follow-up on a large majority of these cases.

Additional Information

We have prepared a rather comprehensive review of the entire subject of Pituitary Tumors and urge you to consider taking time to consult that reference which is available in the Downloads & Information section in this website.

In addition, there are many websites devoted to the Pituitary Gland and Pituitary Tumors. Some of these are reliable, while some are misleading. We can recommend, as an adjunct, the website of The Pituitary Network Association as a reliable primary resource.



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This page last edited on 2/19

All content ©2016 by Neurosurgical Consultants, P.A.
Author, Martin L. Lazar, MD, FACS
All Rights Reserved. See Usage Notices.