what is a benign tumor

A benign tumor is an abnormal growth of cells that does not invade neighboring tissue or metastasize (spread throughout the body) . Unlike malignant (cancerous) tumors, benign tumors generally have a slower growth rate and are not invasive. They are often surrounded by an outer surface (fibrous sheath of connective tissue) or stay contained within the epithelium. Benign tumors are not usually problematic, but they can become large and compress nearby structures, causing pain or other medical complications. Some benign tumors also have the potential to become cancerous when abnormal cells continue to divide out of control. Common examples of benign tumors include moles, uterine fibroids, and lipomas. The word "benign" means "not malignant," i.e., not cancerous.