- Cyst
- Fibroadenoma
- Phyllodes tumor
- Abscess
- Galactocele
- Fat necrosis
- Cyst: non-tender, may change in size slowly
- Fibroadenoma: most common lesion found in young women
- Fibrocystic changes: glandular thickening, pain associated with menses, often bilateral
- Phyllodes tumor: uncommon, mostly middle-aged women. Usually grow rapidly
- Breast abscess: in nursing women, painful, red, growing
- Galactocele: fluid-filled cysts in nursing women
- Fat necrosis: rare, seen mostly with trauma
- Cyst: discrete mass, not hard, non-tender
- Fibroadenoma: small, round, firm, mobile, and non-tender
- Breast abscess: area of redness, pain, and sometimes drainage