Which of the following is not a characteristic of malignant tumors?

• A. Metastasis
• B. Infiltrates surrounding tissues
• C. Encapsulated
• D. Poorly differentiated cells

Answer: (C)

The key idea here is how malignant tumors behave compared with benign ones. Malignant tumors are invasive and disorganized: they spread into surrounding tissues (infiltration) and can travel to distant sites (metastasis). Their cells often look poorly differentiated, meaning they lack the specialized features of the tissue they come from and tend to have a high rate of mitosis. Because of this aggressive, infiltrative nature, malignant growths usually do not have a true capsule surrounding them.

Encapsulation is a feature more typical of benign tumors. A capsule helps keep a benign tumor well circumscribed and contained, so it doesn’t invade nearby structures. That’s why encapsulation is not characteristic of malignant tumors, which tend to break through their boundaries and spread.