Most common intracranial neoplasm
**Core Concept**
The most common intracranial neoplasm is a type of brain tumor that arises from the brain tissue itself, rather than a metastasis from another primary site. This neoplasm is typically a type of glioma, which originates from glial cells that provide support and structure to the brain.
**Why the Correct Answer is Right**
The correct answer is a type of astrocytoma, specifically a World Health Organization (WHO) Grade II astrocytoma, also known as a diffuse astrocytoma. This type of tumor is characterized by the uncontrolled growth of astrocytes, which are a type of glial cell. The tumor cells often have a mix of astrocytic and oligodendrocytic features, and they can infiltrate surrounding brain tissue. The diffuse astrocytoma is the most common type of glioma and accounts for about 50-60% of all gliomas.
**Why Each Wrong Option is Incorrect**
**Option A:** Oligodendroglioma is a type of glioma that arises from oligodendrocytes, but it is less common than astrocytoma and typically has a better prognosis.
**Option B:** Meningioma is a type of tumor that arises from the meninges, the protective membranes surrounding the brain and spinal cord, but it is not a primary brain tumor.
**Option C:** Ependymoma is a type of tumor that arises from ependymal cells, which line the ventricles and central canal of the spinal cord, but it is less common than astrocytoma.
**Clinical Pearl / High-Yield Fact**
The most common presenting symptom of a diffuse astrocytoma is a seizure, followed by focal neurological deficits such as weakness or numbness on one side of the body.
**Correct Answer: C. Astrocytoma**