I was diagnosed with Breast Cancer in March 2007. I had to do a mastectomy as the lump was under the nipple and as the nipple could not be spared, a mastectomy was recommended. Subsequently found that it was DCIS though my 16 lymph nodes were removed during surgery. The Mass was 6cms. Radiation and Tamoxifen was recommended. Radiation lasted 5 weeks daily. Tamoxifen for 5 years. Since doing radiation developed a cough and fever etc. This was sorted out eventually after doing a CT Scan and finding that the lungs were fine. About a month ago discovered a hardened, painful lump within the radiated section near the epi-gastric area. This was ultrasounded and a CT Scan and Fine Needle Biopsy done. Found to be benign and was advised this was "Fat Necrosis." Would like to know what causes fat necrosis and what can be done when it occurs as it is not getting any smaller and seems to be increasing in size.