[The case of a giant malignant phyllodes tumor of the breast]

A 75-year-old female patient complained of a mass in her left breast 2 years ago. The patient experienced a rapid enlargement of the mass 2 months later and visited our hospital. A computed tomography (CT) scan indicated a 25-cm tumor with infiltration of the left breast skin. Pectoral muscle invasion was considered. Swelling of the axillary lymph node and remote metastases were not found. A needle biopsy indicated a phyllodes tumor. A pectoral muscle-preserving mastectomy was undertaken. The tumor weighed 7.1 kg. Pathological examination indicated hyperplasia of the stroma and part of the epithelium, which had invaded the skin layer and fatty tissue. The pathological diagnosis was a malignant phyllodes tumor. This paper reports the case of a giant malignant phyllodes tumor.