What characterizes a malignant tumor?

A malignant tumor is characterized as a cancerous tumor, which means it has the ability to invade nearby tissues and potentially spread to other parts of the body through the bloodstream or lymphatic system. This invasive behavior is what distinguishes malignant tumors from benign tumors, which do not invade surrounding tissues or metastasize. The cells in a malignant tumor often exhibit abnormal growth patterns and characteristics, making them more aggressive and dangerous.

In contrast, benign growth refers to non-cancerous tumors that do not have the ability to spread or invade surrounding tissues. Non-cancerous options, like benign tumors, do not present the same risks as malignant tumors. Inflammatory diseases, while they may cause tissue changes, do not constitute tumors or specifically characterize malignancy. Therefore, the defining characteristic of a malignant tumor being cancerous and capable of aggressive behavior is what makes this answer correct.