How does a benign tumor form a capsule?

A benign tumor forms a capsule as a result of the body's immune response to the tumor. When abnormal cells begin to grow, surrounding tissues often react by creating a fibrous capsule made of connective tissue. This capsule serves to isolate the tumor from the surrounding healthy tissue, preventing it from invading nearby structures. The encapsulation is a characteristic feature of benign tumors, distinguishing them from malignant tumors, which typically lack such a defined boundary.