Pituitary Adenomas

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Introduction

Pituitary adenomas are present in 20-25% of "normal" adults, as shown by MRI. Clinically significant adenomas appear most often from the thirties to fifties.

Pituitary adenomas account for about 10% of intracranial neoplasms and are discovered incidentally in up to 25% of routine autopsies.

The most common cause of hyperpituitarism is an adenoma arising in the anterior lobe.

Prolactinomas are the most common type of functioning adenoma, accounting for up to 30% of all clinically recognized tumours.

Tumours under 1 cm are termed microadenomas, while those over 1 cm are called macroadenomas.

 

 

 

The Case of...

a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.

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Causes and Risk Factors

About 3% of pituitary adenomas are associated with multiple endocrine neoplasia (MEN) type I, though most are isolated lesions.

G-protein mutations are the best-characterized molecular abnormalities. G proteins play a critical role in hormonal signal transduction. Ras and MYC mutations confer a more aggressive phenotype.

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Pathophysiology

Pituitary adenomas are usually composed of a single cell type and produce a single hormone, though some can secrete more than one.

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Signs and Symptoms

Pituitary adenomas can be functional, producing excess hormones, or silent, not causing any noticable effects.

Adenomas of various types produce mass effects, including:

Prolactinomas have a tendency to calcify. Increased prolactin levels (hyperprolactinemia) cause amenorrhea, galactorrhea, loss of libido, and infertility.

 

30-35% of all pituitary tumours are non-functional, with most of these producing LH or FSH.

 

  • history
  • physical exam

History

 

Physical Exam

 

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Investigations

  • lab investigations
  • diagnostic imaging

Lab Investigations

Diagnostic Imaging

 

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Treatments

 

With microadenomas, hormone control is important.

For prolactinomas, dopamine agonists such as bromocriptine or cabergoline can be used. About 20% of people are resistant to dopamine agonists.

 

Surgery can be done for macroadenomas.

Stereotactic radiosurgery can be done as well.

 

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Consequences and Course

 

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Patient Education

 

 

 

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Community Resources

 

 

 

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Resources and References

 

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Topic Development

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