A
benign tumor is a mass of
cells (
tumor) that lacks the ability to invade neighboring
tissue or
metastasize. These characteristics are required for a tumor to be defined as
cancerous and therefore benign tumors are non-cancerous. Also, benign tumors generally have a slower
growth rate than
malignant tumors and the tumor cells are usually more
differentiated (cells have normal features).<ref
name="isbn0-443-10101-9"> Benign tumors are typically surrounded by an outer surface (fibrous sheath of connective tissue) or remain with the epithelium. Common examples of benign tumors include moles and uterine fibroids.