Abstract
A hydatid cyst of the breast is extremely rare, even in endemic areas. There are few reports of breast hydatid cysts. We report a case of an isolated hydatid cyst of the breast that was identified as a painless breast lump that had increased in size just after completion of breast feeding and was present with a painful breast mass after 25 years. This may indicate the possibility of retrograde passage of an Echinococcus granulosus egg through lactating ducts during breast feeding, liberation of an embryo that penetrates ductal mucus and enters the breast tissue and then develops into a hydatid cyst. When a patient comes from an area with little healthcare and where hydatid cysts are epidemic, and if this disease was indicated by radiologic or serologic examination, total mass excision without spillage is the best diagnostic and treatment.