A 71-year-old woman with a past medical history notable for stage IIIB rectal cancer (diagnosed and treated 3 years earlier) presents with complaints of her “eyes not working.” When asked for clarification, she reports experiencing “cloudy vision” for several years but denies any significant changes in the months prior to this evaluation.
Physical exam is notable for incongruent bitemporal visual field defects. The remainder of her exam is unremarkable. A recently obtained carcinoembryonic antigen test is negative (1.0 ng/mL; normal range, < 3.0 ng/mL). All of her other lab values are also within normal limits. Chest CT from 1 month prior re-demonstrated stable pulmonary nodules but was otherwise unremarkable.
An MRI of the brain with gadolinium contrast was obtained and the results are shown here.
This patient eventually underwent a right frontal craniotomy with subtotal resection of the tumor. Subsequent pathologic examination of the tumor gave the definitive diagnosis of WHO grade 1 meningioma. Unfortunately, there was little improvement in the patient’s symptoms, and a postoperative brain MRI showed residual disease extending into the sella turcica with mild compression of the pituitary gland. Adjuvant radiation therapy was recommended to further reduce the size of the meningioma and decrease surrounding tissue compression.
Though the patient has a history of stage IIIB rectal cancer, dural metastasis is an unlikely diagnosis given the low incidence of brain metastases in colorectal cancer (~2%) and the radiologic findings. Common morphologic characteristics of a meningioma include the appearance of a clearly circumscribed, unilobular mass with sharp margins and displacement of surrounding cortical gray matter. This contrasts with glioblastomas which, in general, have irregularly thick margins with an irregular hypodense center (necrotic tissue) and a marked mass effect with significant vasogenic edema. The fact that the patient has normal blood work points away from a pituitary macroadenoma, which is often accompanied by marked hormonal imbalances.
1. Lemke J, Scheele J, Kapapa T, et al. Brain metastases in gastrointestinal cancers: is there a role for surgery? Int J Mol Sci. 2014;15:16816-30.