Section: USMLE

21) An adult patient presents with persistent headaches. A CT scan of the head demonstrates a 2-cm spherical mass at the junction of the white and gray matter of the lateral aspect of the cerebral hemisphere. Which of the following would most likely produce this lesion?

1. Astrocytoma
2. Ependymoma
3. Glioblastoma multiforme
4. Meningioma
5. Metastatic carcinoma

Seventy percent of adult brain tumors occur above the tentorium (70% of childhood tumors occur below the tentorium). Statistically, metastases > astrocytomas (including glioblastoma) > meningioma > pituitary tumor. Location at the junction of cortical gray and white matter is also typical for metastatic disease, as is the round shape.

Astrocytomas typically arise in the white matter and have an irregular shape.

Ependymomas are uncommon and arise from the ependymal lining of the ventricles.

Glioblastoma multiforme is an aggressive form of astrocytoma that can cause a “butterfly lesion,” crossing between the cerebral hemispheres.

Meningiomas can cause spherical lesions and are usually located on the surface of the brain.