A 64-year-old man presents with headache and left-sided upper extremity weakness. The MRI findings suggest that this is a glioblastoma multiforme. This is because the tumor exhibits which of the following?
**Core Concept**
The question is testing the understanding of the histopathological characteristics of glioblastoma multiforme (GBM), a highly aggressive and malignant primary brain tumor. GBM is characterized by a mixture of cellular elements, including neoplastic cells, necrosis, and vascular proliferation.
**Why the Correct Answer is Right**
Glioblastoma multiforme exhibits a high degree of **vascular proliferation**, which is a hallmark feature of this tumor type. Vascular proliferation in GBM is characterized by the formation of abnormal blood vessels with thickened walls and irregular lumens. This leads to increased vascularity and a characteristic "pseudo-vascular" appearance on histopathological examination. The increased vascularity also contributes to the tumor's aggressive behavior and poor prognosis.
**Why Each Wrong Option is Incorrect**
**Option A:** While GBM does exhibit cellular pleomorphism, which refers to the variation in size and shape of tumor cells, this feature is not unique to GBM and can be seen in other types of gliomas.
**Option B:** Necrosis is a common feature of GBM, but it is not the primary reason why this tumor is diagnosed as GBM. Necrosis can be seen in other types of tumors as well.
**Option C:** Microcalcifications can be seen in GBM, but they are not a diagnostic hallmark of this tumor type.
**Clinical Pearl / High-Yield Fact**
Glioblastoma multiforme is the most common primary brain tumor in adults, and it has a poor prognosis despite aggressive treatment. The World Health Organization (WHO) classification of tumors of the central nervous system (CNS) grades GBM as a Grade IV tumor, indicating its high malignant potential.
**Correct Answer:** C.