Pituitary incidentalomas.

Incidental pituitary masses are commonly found during CT and MR imaging performed for a variety of reasons. Screening for hormone oversecretion by these tumors seems to be warranted. Patients with lesions greater than 1 cm should 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 MR imaging scans. A limited amount of data suggest that significant tumor enlargement occurs in less than 5% of patients with lesions smaller than 1 cm in diameter. However, all macroadenomas must start out as microadenomas, and thus periodic follow-up is indicated to assess for this possibility. Lesions larger than 1 cm in diameter by their very existence at the time of detection have already indicated a propensity for growth. Significant tumor growth occurs in just over one-quarter of such patients. 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 or octreotide is reasonable, realizing that only 10% of such patients will respond with a decrease in tumor size. Alternatively, careful periodic observation without intervention may determine that the lesion is not growing. Surgery is indicated with 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.