The most common pituitary macroadenomas seen in adults are classified as clinically nonfunctioning pituitary adenoma (NFPA). Although termed nonfunctioning, many display positive immunostaining for gonadotropins LH and FSH, whereas "silent" corticotroph and somatotroph tumors may also occur. Presentation may be incidental when neuroimaging has been performed for reasons other than pituitary assessment. Alternatively, a macroadenoma causes mass effects including headache and visual failure. In general, pituitary function is preserved in early cases, although hyperprolactinemia related to disinhibition related to stalk compression is frequently present. As the tumor enlarges, progressive loss of GH, the gonadotropins, and eventually ACTH and TSH axes will occur.
In macroadenomas, surgical treatment is indicated, with the transsphenoidal route favored. In those patients with preoperative hypopituitarism, recovery of hormone secretion may occur (31). The recurrence rate of NFPA treated by surgery alone is considerable (26), and many centers advocate the use of radiotherapy in most patients after surgery. However, improvements in neurosurveillance, largely MRI, may allow patients to be followed closely in the absence of radiotherapy. Review of pituitary function and replacement of pituitary hormones should follow the protocol set out for acromegaly earlier. Periodic rescanning should be performed because recurrences may occur years after primary treatment. With standard radiotherapy (as detailed in Chapter 13), recurrence will be less, probably considerably less than 5%.
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