Phyllode tumors are rare fibroepithelial neoplasms divided into three histological grades according to their potential for malignancy. Low grade tumors are usually smaller with a slower evolution.

We present here the case of a 40 year old women presenting an augmentation over one month of the volume of her right breast with an ulcerated mass measuring 25cm. The clinical characteristics were in favor as a malignant tumor. The radiological findings were not contributive and the pathologic examinations of the biopsies were benign. A therapeutic and diagnostic mastectomy was thus performed and the final pathologic examination confirmed a benign phyllode tumor.

These rare tumors are very deceitful for the radiologic investigations are poorly contributive. Likewise, the pathologic examination can be incorrect. Biopsies must be repeated and a mastectomy performed if any doubts remain.