Ah yes, now I know what it is (I checked my notes)! I forget what I learnt it was called, but Inflammatory Breast Cancer is an Americanism it was named after the person who discovered it I think, somthing beginning "von" although that might be a skin cancer! it occures quite deep in the breast so you may not actually feel a lump, but it blocks lots of smaller lymph nodes, causing swelling as lymph fluid is trapped in the breast tissue. "normal" breast cancer (if there is such a thing) usually occures in the mammary glands which are much closer to the surface.
Inflammatory breast cancer is not usually treated with Tamoxifen as it usually has no oestrogen receptors, it is also much more difficult to eradicate as cancer cells are more likely to mestasise and settle in different areas of the lymphatic system.
Very nasty. One of the cell lines that I am experimenting on has similar properties. My advice is to eat lots of oily fish, it appears to have some protective properties.