Hello, mass in breast may be due to do many causes you need to undergo complete evaluation. Common causes are Breast cysts — fluid-filled sacs in your breast that are usually benign Fibroadenoma — a solid, benign mass most common in young women Fibrocystic breasts — lumpy or rope-like breast tissue 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 Milk cyst (galactocele) — a milk-filled cyst that's usually harmless Cancer. Kindly consult general surgeon for evaluation and treatment. He will suggest investigations according to its appearance.