Tumors that mimic pituitary adenomas because of their location

From Lewis S. Blevins, Jr. MD  –  This patient presented with headaches and vision loss. The MRI was said to show a pituitary adenoma. It is, however, clear that this is a tuberculum sellae meningioma. These tumors arise from the dura mater in and about the region of the tuberculum in the sella turcica. They can mimic pituitary tumors because of their location. Most patients present with visual disturbances and headaches.

Rarely, patients will have a loss of smell, seizures, neuropsychiatric disorders, or other neurological changes. Though the tumors my extend into and fill the sella, pituitary function is rarely abnormal. In contrast, pituitary adenomas this large would usually cause pituitary dysfunction. Notably, the sella turcica is often of normal size as is seen in this patient whereas the sella is often enlarged in patients with pituitary adenomas.

The anterior or forward portion of this tumor had a dural tail characterized by tapering of the lesion with an attachment to the durra. Oftentimes, this is said to be beak-like and many of these tumors look like a bird in flight on the sagittal section. This particular tumor looks like a big reverse apostrophe on its side curving over the top of the posterior ethmoid and anterior sphenoid sinuses.

I show this Image as an example that not everything thought to be a pituitary tumor is actually a pituitary adenoma.

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