Clinical review 65. Evaluation and treatment of the patient with a pituitary incidentaloma.

Incidental pituitary adenomas are being found commonly with our improved neuroradiological imaging procedures. Screening for hormone oversecretion by these tumors appears to be warranted. For patients with macroadenomas, patients should also be screened for hypopituitarism. In the absence of visual field abnormalities or hypothalamic/stalk compression, it may be appropriate to observe such patients carefully with repeated CT or MRI scans. A limited amount of data suggests that significant tumor enlargement will occur in less than 15% of patients with microadenomas (7). However, all macroadenomas must start out as microadenomas, so periodic follow-up is indicated to assess this possibility. Macroadenomas, by their very existence at the time of detection, have already indicated a propensity for growth. Over the limited period of follow-up in the two series reported, significant growth occurred in almost one third of patients with macroadenomas (7, 8). Hemorrhage into such tumors is uncommon, but anticoagulation may predispose to this complication. When there is no evidence of visual field deficits, an attempt at medical therapy with a dopamine agonist is reasonable, realizing that only about 10% of such patients will respond with a decrease in tumor size. Surgery is indicated if there is evidence of tumor enlargement, especially when such growth is accompanied by compression of the optic chiasm, cavernous sinus invasion, or the development of pituitary hormone deficiencies.