Brain anatomy PITUITARY GLAND – cross section
As providers, we often order imaging studies that result in unexpected findings. A common incidentally discovered abnormality is a pituitary adenoma, also known as pituitary incidentaloma. However, one must keep in mind that radiologists may over-interpret an anomaly <10 mm as a pituitary microadenoma, 99% of the time. These findings are more likely to occur in an MRI instead of a CT.
As a provider, one should be concerned if the pituitary adenoma is >10 mm or is causing visual or neurological changes. For patients with visual or neurological changes, prompt referral to a neurosurgeon for a transsphenoidal surgery is necessary. If the patient does not present with those warning symptoms but their adenoma is >10 mm, then further clinical workup for hormone hypersecretion and hypopituitarism is indicated. This involves serum prolactin, insulin-like growth factor-1, luteinizing hormone, follicle-stimulating hormone, and alpha subunit corticotropin. If hormone hypersecretion is present one must inhibit hormone production. If hypopituitarism is present, then replacement is indicated.
Follow up care for patients with adenoma’s greater than 10 mm but less than 20 mm without hormonal hypersecretion, visual, or neurological abnormalities consists of the following. Repeating labs in 6 and 12 months and then annually for several years. The MRI should be repeated yearly for several years to monitor for growth because 12% of adenomas can grow and cause issues. On the other hand, for patients with adenoma’s 2-4 mm, no further work-up is needed. For those with lesions 5-9 mm, a prolactin level in addition to a pituitary MRI should be done yearly for two years. If no significant changes in size or levels occur, the frequency of repetition can be reduced.
