Pituitary tumours: pituitary incidentalomas.

Clinically non-functioning pituitary adenomas range from being completely asymptomatic, and therefore being detected either at autopsy or as incidental findings on head magnetic resonance imaging (MRI) or computed tomography (CT) scans performed for other reasons (often referred to as 'pituitary incidentalomas'), to causing significant hypothalamic/pituitary dysfunction and visual field compromise due to their large size. Patients with pituitary incidentalomas should all be screened for hypersecretion (prolactin (PRL), IGF-1, midnight salivary cortisol), and those with macroadenomas should also be screened for hypopituitarism (macroadenomas) and for visual field defects if the tumour abuts the optic chiasm. Growth of non-functioning pituitary adenomas without treatment occurs in about 10% of microadenomas and 24% of macroadenomas. In the absence of hypersecretion, hypopituitarism or visual field defects, patients may be followed up by periodic screening by MRI for enlargement. Growth of a pituitary incidentaloma is an indication for surgery.