Pitutary Adenoma

Pituitary adenomas are tumors that occur in the pituitary gland. Pituitary adenomas are generally divided into three categories dependent upon their biological functioning: benign adenoma, invasive adenoma, and carcinomas. Most adenomas are benign, approximately 35% are invasive and just 0.1% to 0.2 are carcinomas. Pituitary adenomas are the third most common intracranial tumor and arise from the pituitary gland. The estimated prevalence rate in the general population is approximately 17%.

Non-invasive and non-secreting pituitary adenomas are considered to be benign in the literal as well as the clinical sense; however a recent meta-analysis of available research has shown there are to date scant studies – of poor quality – to either support or refute this assumption.

Adenomas which exceed 10 millimetres  in size are defined as macroadenomas, with those smaller than 10mm referred to as microadenomas. Most pituitary adenomas are microadenomas, and have an estimated prevalence of 16.7% (14.4% in autopsy studies and 22.5% in radiologic studies).  A majority of pituitary microadenomas often remain undiagnosed and those that are diagnosed are often found as an incidental finding, and are referred to as incidentalomas.

Pituitary macroadenomas are the most common cause of hypopituitarism, and in the majority of cases they are non-secreting adenomas.

While pituitary adenomas are common, affecting approximately one in 6 of the general population, clinically active pituitary adenomas that require surgical treatment are more rare, affecting approximately one in 1000 of the general population.

How are Pituitary Macroadenomas diagnosed?

Your doctor may suspect you have a macroadenoma if you have the symptoms listed above. Possible tests to confirm this diagnosis include the following:

  • Blood tests

  • Urine tests

  • Visual field tests

  • Computed tomography (CT)

  • Magnetic resonance imaging (MRI)

  • Inferior petrosal sinus sampling (IPSS)

 

SYMPTOMS

Pituitary macroadenomas can cause Cushing’s syndrome, acromegaly, hyperthyroidism, and, rarely, symptoms related to decreased secretion from the pituitary gland. Symptoms of a pituitary macroadenoma can include the following:

  • Headache

  • Problems with eyesight

  • Dizziness

  • Nausea

  • Unexplained hair growth or loss

  • Weight changes

  • Menstrual or breast changes

  • Erectile dysfunction

 

TREATMENT

Treatment options depend on the type of tumor and on its size:

  • Prolactinomas are most often treated with cabergoline or quinagolide (both dopamine agonists), which decrease tumor size as well as alleviates symptoms, followed by serial imaging to detect any increase in size. Treatment where the tumor is large can be with radiation therapy, proton therapy or surgery, and patients generally respond well. Efforts have been made to use a progesterone antagonist for the treatment of prolactinomas, but so far have not proved successful.

  • Somatotrophic adenomas respond to octreotide, a long-acting somatostatin analog, in many but not all cases according to a review of the medical literature.[citation needed] Unlike prolactinomas, thyrotrophic adenomas characteristically respond poorly to dopamine agonist treatment.

  • Surgery is a common treatment for pituitary tumors. The normal approach is Trans-sphenoidal adenectomy, which usually can remove the tumor without affecting the brain or optic nerves.

 

Surgical removal is indicated for the great majority of symptomatic pituitary adenomas with the exception of prolactinomas. Transsphenoidal surgical removal (via the nose) is typically the treatment of choice. Fortunately, pituitary adenoma surgery has had major technical advances over the last two decades, including use of high-definition endoscopy, surgical navigation techniques and more effective skull base closure methods.

The endonasal approach uses the nostrils as natural surgical corridors to remove pituitary adenomas, and many midline skull base & brain tumors.

The endonasal route is the preferred surgical approach for almost all pituitary adenomas and Rathke’s cleft cysts, as well as most craniopharyngiomas and clival chordomas. Utilizing high definition endoscopy (surgical telescope), surgical navigation (“GPS for the brain”) and Doppler ultrasound for carotid artery localization, the endonasal approach has evolved into a safe and effective procedure in experienced hands. Major advantages of the endonasal route are: avoidance of brain retraction, minimal or no manipulation of the optic nerves, no facial incisions and the infrequent need for nasal packing.