True about Epithelioid hemangioendothelioma
**Core Concept**
Epithelioid hemangioendothelioma (EHE) is a rare, malignant vascular tumor that arises from the endothelial cells lining blood vessels. It is characterized by its epithelioid morphology, which distinguishes it from other vascular tumors.
**Why the Correct Answer is Right**
EHE typically affects the liver, lungs, and bone, and is often associated with a good prognosis due to its indolent nature. The tumor cells exhibit a range of differentiation, from poorly differentiated to highly differentiated, and may express markers such as CD31, CD34, and Factor VIII-related antigen. The pathogenesis of EHE is not fully understood, but it is believed to involve mutations in the WWTR1-CAMTA1 fusion gene, which leads to the activation of the Hippo signaling pathway.
**Why Each Wrong Option is Incorrect**
**Option A:** EHE is not typically associated with a high level of aggressiveness, unlike other vascular tumors such as angiosarcoma. This option is incorrect because EHE is generally considered to have a more indolent course.
**Option B:** While EHE can affect the liver, it is not exclusively a liver tumor, and can also occur in the lungs and bone. This option is incorrect because EHE has a wide range of possible locations.
**Option C:** EHE does not typically express a specific set of markers that are unique to this tumor. This option is incorrect because while EHE may express markers such as CD31 and CD34, these are not exclusive to this tumor.
**Clinical Pearl / High-Yield Fact**
EHE is a rare and often misdiagnosed tumor, and a high index of suspicion is required for accurate diagnosis. A thorough evaluation of the patient's clinical presentation, imaging studies, and histological features is necessary to establish a diagnosis of EHE.
**Correct Answer:**