A 50-year-old woman undergoes neurosurgery for resection of a well-circumscribed intracranial neoplasm attached to the dura. The tumor compressed the underlying brain parenchyma without infiltration. Which of the following is the most likely diagnosis?
**Core Concept**
The question is testing the student's knowledge of intracranial neoplasms and their characteristics, particularly their behavior and relationship with surrounding tissues. Well-circumscribed neoplasms that compress the brain parenchyma without infiltration are typical of certain types of tumors.
**Why the Correct Answer is Right**
Meningiomas are a type of tumor that arise from the meninges, the protective membranes surrounding the brain and spinal cord. They are typically well-circumscribed, slow-growing, and compress the underlying brain parenchyma without infiltrating it. This characteristic behavior is due to the fact that meningiomas are usually benign and have a distinct border from the surrounding brain tissue. They often attach to the dura, a common location for meningiomas to arise.
**Why Each Wrong Option is Incorrect**
**Option A:** An arteriovenous malformation (AVM) is a vascular anomaly that consists of abnormal connections between arteries and veins, but it is not a neoplasm and does not typically compress the brain parenchyma in the same way as a well-circumscribed tumor.
**Option B:** Glioblastoma multiforme (GBM) is a type of malignant brain tumor that arises from glial cells and is characterized by rapid growth, infiltration into surrounding brain tissue, and poor prognosis. It does not typically present as a well-circumscribed neoplasm.
**Option C:** Medulloblastoma is a type of malignant brain tumor that arises from the cerebellum and is more common in children. It can present as a well-circumscribed mass, but it often has a more aggressive behavior and infiltrates surrounding brain tissue.
**Clinical Pearl / High-Yield Fact**
Meningiomas are often associated with dural attachment and can be resected surgically, making them a favorable diagnosis for patients with a well-circumscribed intracranial neoplasm. However, some meningiomas can be challenging to remove due to their proximity to critical brain structures.
**✓ Correct Answer: D. Meningioma**