Hi Hilda, phyllodes tumours are very fast growing so it could be a combination of all the things you have mentioned. If you are on facebook I would recommend joining the phyllodes support group as they have lots of information in a closed group too. When you have your surgery make sure that you insist on clear margins of at least 1cm even though your tumor from biopsy was classed as benign. Unfortunately they cannot tell the grade of the tumour from biopsy alone - you will find out the grade of your tumour once it has been removed. Best to get a good margin in the first instance than having to go back for more surgery to get wide margins. I hope this helps. Best wishes. Katie.