Pituitary tumor: Basic Important facts
The pituitary gland is a small gland found at the base of the brain. The gland has two parts, the posterior (back) pituitary and the anterior (front) pituitary. This gland sits within a small bone cavity called the sella turcica that is located behind the eye sockets and the nose sinuses.
The pituitary gland sits right beneath the Optic Chiasm which is the confluence of our two optic nerves. On both sides of the sella, Internal carotid arteries pass which supply almost two-third of our brain. and nerves pass close to the pituitary gland in an area called the cavernous sinus (sinus cavity).
What are the hormones produced by the Pituitary gland?
Pituitary gland is called the Master Gland of the body as it controls most of the important hormones of the body, directly or indirectly. It is a key link between the brain and other glands in the body.
The anterior pituitary makes many hormones:
Prolactin is a hormone that is needed to make breast milk.
• ACTH controls steroids made by the adrenal gland.
• TSH controls the thyroid.
• Two other hormones (FSH and LH) control the production of sex hormones and fertility.
• Growth hormone is responsible for linear growth and height in children and maintenance of bone and muscle mass in adults.
The posterior part of the pituitary is a direct extension of the brain and stores two hormones:
• Antidiuretic hormone works on the kidneys to regulate water loss.
• Oxytocin controls contractions when a woman goes into labor.
What are Pituitary tumors?
A pituitary tumor is an abnormal growth of cells in the pituitary gland. Almost all tumors begin in the anterior pituitary. Depending upon the size the Pituitary tumors are called ‘Microadenomas’ if they are <10mm, or ‘Macroadenomas’ if they are >10mm in size.
How are pituitary tumors classified?
Based on size they are Microadenomas or Macroadenomas.
Another way of classifying the Pituitary tumors is based on their production of hormones. Majority of tumors are non-functional tumors, that is they do not overproduce any hormone. Functional tumors produce excess of a particular hormone.
How do Non-functional Pituitary tumors present?
As these tumors do not produce any hormones, the manifestations are related to the size of tumor and pressure on the adjacent structures of the brain and nerves. A tumor may:
• Cause the pituitary gland to make too many or too few hormones.
• Cause vision loss if it causes pressure on the optic nerve or more commonly Optic chiasm
• Cause difficulty with eye movement if it pushes on nerves responsible for eye movements.
• Cause headaches
• Cause no symptoms at all, detected incidentally, called ‘Incidentalomas’
How do the functional Pituitary tumors manifest?
Functional Pituitary tumors present because of overproduction of hormones leads to different manifestations.
Acromegaly or Gigantism- Because of excess of Growth hormone.
Cushings Disease- Because of excess of ACTH production, thereby increasing Endogenous steroid production.
Prolactinomas- Cause abnormal milk production from breasts, stops menstrual cycles, and excessive facial hair growth.
TSH producing tumors- Tumors that cause excess production of thyroid hormones are very rare.
Is Pituitary tumor a cancer?
Most pituitary tumors are benign, that is they have a slow growth rate and do not spread to other areas of the body unlike cancer. Pituitary cancer is very rare.
What are the Risk Factors for Pituitary tumors?
As of now, we do not know for sure what causes pituitary tumors. Pituitary tumors can happen at any age, but they are more common in older adults. Having a family history of the disease called multiple endocrine neoplasia type 1 (MEN1) raises the risk of pituitary tumors.
What is Cushing’s disease?
Cushing’s disease is when Adrenocorticotropic hormone-producing tumors of Pituitary cause the adrenal glands to make more of a hormone called cortisol.
• Weight gain around the stomach area and upper back
• Round or swollen face, ‘Moon Like facies’
• Stretch marks that are usually wide and purple in color
• Hump on the upper back and excessive fat above the collar bones
• High blood pressure
• High blood sugar
• Muscle weakness
• Thinning of the skin
• Easy bruising
• Abnormal periods and excessive hair growth (in women)
• Osteoporosis and broken bones
When these features are present it is called Cushing’s syndrome. Cushing’s disease is the specific name given to these symptoms being specifically caused by a Pituitary tumor.
What is Acromegaly and Gigantism?
These are caused by excess of growth hormones in the body.
Growth hormone-producing tumors in adult’s cause
• Rough or coarse facial features, such as enlarged jaw and prominence of forehead
• Enlarged hands and feet
• High blood pressure
• Heart problems, increase in size of heart muscle thereby weakening heart function.
• Excessive sweating
• Respiratory disorders such as sleep apnea
• Enlargement of the tongue and widening of the spaces between the teeth
• Arthritis and joint pains
• Excessive growth (gigantism) in children
If the excessive growth hormones is present in growth phase of children, that is before fusion of bone growth plates, the it causes abnormal increase in overall length of individual and limbs, causing Gigantism.
What are Prolactinomas?
Prolactin-producing tumors make too much of the hormone called prolactin.
High amounts of prolactin in the blood affect women and men differently.
For women, it may cause:
• Irregular or no menstrual periods, called Amenorrhoea
• Milky discharge from the breasts, Galatorrhoea
In men, it may cause:
• Enlarged breasts
• Erectile dysfunction (ED) or impotence
• Less body hair
• Loss of interest in sex
In children it may cause a delay in puberty.
How are Pituitary tumors diagnosed?
Sometimes Pituitary tumors may be found incidentally on a scan done for some other reason.
Magnetic resonance imaging (MRI) is the gold standard imaging for the brain to detect these tumors. CT scan is not very helpful in delineating this tumor. MRI is done with contrast and dynamic MR is better to pick up small pituitary tumors.
What are the other tests done for Pituitary tumors?
Complete hormonal blood profile is mandatory to look for baseline of all hormones, so that any deficiency of a particular hormone can be tackled fast.
Visual field charting, or Perimetry is to look for damage to your optic nerves from the pressure of tumor.
What is the treatment of Non-functional tumors?
If the tumor is incidentally detected and is not causing any significant pressure of vision pathways, the it can be observed sequentially with interval MRI and visual field charting.
For larger tumors, surgery is mandatory. Trans-nasal endoscopic route is considered the best way of surgery in current practice. It is performed by a tem od Neurosurgeons and ENT surgeons, using the nasal cavity.
However, if the tumor is very large, or going out of its normal bony walls into other areas of brain, then t may not be feasible and the surgeon may opt for a trans-cranial route.
After surgery scans are done, around 3 months after surgery to see for any residue which if present can be observed or can be treated with a single high dose of radiation using Gamma Knife.
How are functional pituitary tumors treated?
Treatment depends on the hormone which is being over-produced by the tumor.
In Prolactinomas, medical treatment is the first option. The tumor is documented to just disappear with medical treatment no matter how large it was to begin with. Cabergoline is the drug of choice for this tumor, and needs to be taken twice weekly. Dose can be adjusted as per the clinical and lab response. Surgery may be required in case tumor does not respond, medicines are not tolerated or CSF starts leaking after initiation of the drug.
For other functional tumors, like Cushing’s disease or Acromegaly, surgical removal of the tumor is must. However, it may not completely solve the problem of overproduction of hormone, and some adjuvant form of medical therapy may be required to further suppress the hormone production.
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