I had not ever heard of this before now, but there is a cancer known as inflammatory breast cancer that does NOT present itself with lumps.
The symptoms vary and are vague which makes this cancer even scarier and from what I have heard more deadly than regular breast cancer. To see a video news report go to http://www.topsiecurvey.blogspot.com/
Remember also that breast cancer is not confined to females only. A small percentage of men also get the disease and can die from it. Everyone should check for lumps and be aware that any changes such as rashes, dimpling, or changes in appearance should be cause for a visit to the doctor.