The natural history of the pituitary incidentaloma

The wide availability of computed tomography and magnetic resonance imaging has resulted in the discovery of unsuspected endocrinologically silent pituitary masses (incidentalomas). Because the natural history of this entity is not known, the approach to the pituitary incidentaloma has not been established.

To determine the natural history of untreated pituitary incidentaloma, recognizing that this includes lesions of various causes.

Thirty-one adults with incidentalomas were prospectively followed up conservatively for a mean of 6.4 years (range, 3 to 11 years). Clinical and biochemical assessment, computed tomography or magnetic resonance imaging of the pituitary, and visual field testing by Goldmann perimetry at baseline, 6 months, and yearly thereafter were the outcomes assessed.

Only patients with pituitary incidentalomas greater than 10 mm in greatest diameter developed tumor enlargement or complications. Three patients developed asymptomatic tumor enlargement. In four patients, masses decreased in size. Only two patients developed complications. One required subsequent surgery. The only permanent impairment was panhypopituitarism following surgery in this patient.

Patients with pituitary incidentalomas of unknown causes usually follow a benign course for at least 6 years after discovery. Neurosurgical intervention is not initially required in the management of is not initially required in the management of pituitary incidentalomas, particularly those less than 10 mm, as long as clinical observation can be continued.