Pituitary space-occupying lesions and tumours

Pituitary tumours are the most common cause of pituitary disease. Problems may be caused by:

• Excess hormone secretion
• Local effects of the tumour
• The result of inadequate production of hormone by the remaining normal pituitary (hypopituitarism)

The great majority of pituitary tumours are benign pituitary adenomas

Investigations:

The investigation of a possible or proven tumour follows three lines:

1. Is there a tumour?
2. Is there hormonal excess?
3. Is there a deficiency of any hormone?

Is there a tumour?

Pituitary and hypothalamic space-occupying lesions can cause symptoms by infiltration of or pressure on, the:

• Visual pathways
• Cavernous sinus (with III, IV and VI cranial nerve lesions)
• Bony structures and meninges surrounding the fossa (causing headache)
• Hypothalamic centres (can cause altered appetite, thirst, somnolence/wakefulness or precocious puberty
• Ventricles (causing interruption of CSF flow, leading to hydrocephalus)

The principle investigations when looking for a pituitary tumour are:

• Lateral skull X-ray
• Tests of the visual fields
• MRI of the pituitary

Is there hormonal excess?

There are 3 major conditions that may be caused by tumour or hyperplasia:

1. GH excess (leading to acromegaly or gigantism)
2. Prolactin excess
3. Cushing’s disease (caused by excess ACTH secretion)

Is there a deficiency of any hormone?

Clinical examination may give clues, thus:

• Short stature in a child with a pituitary tumour is likely to be due to GH deficiency
• A slow, lethargic adult with pale skin is likely to be deficient in TSH and/or ACTH

Treatment:

In general, treatment of a pituitary space-occupying lesion has 3 aims:

1. Removal/control of tumour
2. Reduction of excess hormone production
3. Replacement of hormone deficiencies