THE NATURAL-HISTORY OF THE PITUITARY INCIDENTALOMA

Background: The wide availability of computed tomography and magnetic resonance imaging has resulted in the discovery of unsuspected endocri nologically silent pituitary masses (incidentalomas). Because the natu ral history of this entity is not known, the approach to the pituitary incidentaloma has not been established. Objective: To determine the n atural history of untreated pituitary incidentaloma, recognizing that this includes lesions of various causes. Methods: Thirty-one adults wi th incidentalomas were prospectively followed up conservatively for a mean of 6.4 years (range, 3 to 11 years). Clinical and biochemical ass essment, computed tomography or magnetic resonance imaging of the pitu itary, and visual field testing by Goldmann perimetry at baseline, 6 m onths, and yearly thereafter were the outcomes assessed. Results: 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 de creased in size. Only two patients developed complications. One requir ed subsequent surgery. The only permanent impairment was panhypopituit arism following surgery in this patient. Conclusions: Patients with pi tuitary incidentalomas of unknown causes usually follow a benign cours e for at least 6 years after discovery. Neurosurgical intervention is not initially required in the management of pituitary incidentalomas, particularly those less than 10 mm, as long as clinical observation ca n be continued.