Malignant, locally recurring cystosarcoma phyllodes in an adolescent female. A case report.

A 16-year-old girl presented with a large and rapidly growing cystosarcoma phyllodes in her right breast. The excised tumour showed unequivocal malignant characteristics at light and electron microscopy and was oestrogen-receptor negative. After repeated early local recurrences, a subcutaneous mastectomy ultimately led to local tumour control and the patient is now disease free 5.5 years after diagnosis.