Meningioma and Underlying Brain

Twenty-eight non-operated supratentorial meningiomas were selected from the autopsy files of Montefiore Hospital to study the relationship between the brain and the tumor. Though meningiomas are usually well demarcated from the brain, their interface with the brain takes various forms, i.e., smooth type, lobular type, finger-like expansion type, and invasive type. The so-called “capsule” mainly consists of arachnoid membrane, arachnoid trabeculae, septae of the tumor and pial membrane. In several cases, there is no obvious connective tissue that can be called a “capsule” between the tumor and the brain. Vessels in the subarachnoid space are located between lobules of the tumor or surrounded by connective tissue. Sometimes, they are completely entrapped in the tumor. Loss of neurons, gliosis, cyst formation, edema and even calcification are seen in the underlying brain. The thickness of the underlying cortex does not always depend on the size of the tumor. Even small meningiomas, 2-3 cm in diameter, are sometimes associated with a thin cortex.