Clinics in diagnostic imaging (84). Galactocoele.

A 37-year-old woman who was six months postpartum presented with a painless lump in her left breast for three months. Mammograms showed a mixed fat and soft density mass on the craniocaudal and mediolateral views. A fat-fluid level was seen within the mass, typical of a galactocoele. Needle aspiration yielded milky fluid. The differential diagnosis of breast masses presenting in women with pregnancy or lactation is briefly discussed. The other causes of fat containing breast masses, such as oil cyst, hamartoma, lipoma and intramammary lymph nodes, are illustrated with additional examples.