Benign tumor is a tumor (i.e. mass of cells) that LACKS the ability to invade neighboring tissue or metastasize. These characteristics are required for a tumor to be cancerous, and thus benign tumors are NON-cancerous.

• Benign tumors generally have a slower growth rate than malignant tumors, and the tumor cells are usually more differentiated (cells have normal features)
• Benign tumors are typically surrounded by an outer surface (fibrous sheath of connective tissue), or remain w/ the epithelium

• Endodermal:
  • Cholangioma
  • Colonic polyp
  • Adenoma
  • Papilloma
  • Cystadenoma
  • Liver cell adenoma
  • Hydatiform mole
  • Renal tubular adenoma
  • Squamous cell papilloma
  • Gastric polyp
• Mesenchymal:
  • Hemangioma
  • Osteoma
  • Chondroma
  • Lipoma
  • Fibroma
  • Lymphangioma
  • Leiomyoma
  • Rhabdomyoma
• Ectodermal:
  • Astrocytoma
  • Nevus
  • Meningioma
  • Ganglioneuroma

• Removal by surgery, for some benign tumors, due to tumor progression, and possible negative health effects

• Will NOT metastasize or locally invade tissue
• May still produce negative health effects
• Mass effect, that can compress tissue and may cause nerve damage, ischemia (reduce blood to an area of the body), necrosis (tissue death), and organ damage. Mass effect is more prominent if the tumor is w/ in an enclosed space, e.g. the cranium, respiratory tract, sinus, or inside bones
• Tumors of endocrine tissue may overproduce certain hormones, especially when the cells are well differentiated, e.g. thyroid adenomas, and adrenocortical adenomas
• Most benign tumors are NOT life threatening, many types of benign tumors have the potential to become malignant (cancerous), through a process known as tumor progression