Causes

Breast lumps can be caused by:

• Breast cancer
• Breast cysts (fluid-filled sacs in breast tissue that are usually benign)
• Fibroadenoma (a solid, benign mass most common in young women)
• Fibrocystic breasts (lumpy or rope-like breast tissue)
• Galactocele (a milk-filled cyst that's usually harmless)
• Injury or trauma to the breast
• Intraductal papilloma (a benign, wartlike growth in a milk duct)
• Lipoma (a slow-growing, doughy mass that's usually harmless)
• Mastitis (an infection in breast tissue that most commonly affects women who are breast-feeding)