[Cystosarcoma phyllodes].

A rare case of mammary neoplasia is described. Its morphological and cytologic features are ascribed to cystosarcoma phylloides. It's a rare neoplasia since it represents only the 0.3-0.9% of mammary tumors. At present about one thousand of case have been described in literature. Because of its unforeseeable behaviour, cystosarcoma phylloides requires treatment and follow-up different from mammary carcinoma and fibroadenomas. The treatment is surgical only; the choice between an extensive exeresis and a complete mastectomy is related to tumor dimensions.