**Question:** It is true that sarcoma -

A. is a rare cancer
B. occurs only in children
C. is caused by a viral infection
D. is always malignant

**Core Concept:** Sarcoma is a group of rare cancers that develop from connective tissue cells, such as fibroblasts, adipocytes, and endothelial cells. These cells are responsible for forming blood vessels, fat, and connective tissue, respectively. Sarcomas can occur in all age groups, but they are relatively rare compared to other types of cancer.

**Why the Correct Answer is Right:** Sarcoma is characterized as a malignant tumor, meaning it has the potential to invade and spread to other parts of the body (metastasize). In this context, "is always malignant" (option D) is correct as it highlights the crucial feature of sarcoma – its malignant nature.

**Why Each Wrong Option is Incorrect:**

A. "Sarcoma is a rare cancer" (option A) is partially correct, but it fails to capture the full nature of sarcoma, as it is not limited to just children. Sarcoma can develop at any age, though it is more common in adults.

B. "Occurs only in children" (option B) is incorrect as sarcoma can develop in people of all ages, not just children.

C. "Caused by a viral infection" (option C) is incorrect as sarcomas are not directly caused by viruses. Although certain viruses, such as Kaposi's sarcoma, can be associated with certain infections, the majority of sarcomas have unknown causes.

**Clinical Pearl:** Sarcomas are a diverse group of cancers that can affect different organs and tissues. While sarcoma can be associated with viral infections in some cases, the statement "is always malignant" provides a more comprehensive understanding of the disease, encompassing both its rarity and malignant nature.