Hydatid cyst presenting as a breast lump.

Cystic hydatid disease is caused by the parasite Echinococcus granulosus. Indigenous infections are seen among the Indians and Inuit. Man is an occasional intermediate host in whom the disease is manifested by the presence of one or more hydatid cysts, usually located in the liver or lung and rarely at other sites such as the breast, as in this case report. The cyst is usually asymptomatic; in this it case was discovered on routine mammography. On aspiration biopsy, 1 ml of clear fluid was removed, but there was a residual lump which was successfully excised.