How come i have a large breast lump but mammogram and ultrasound show nothing?

Breast Lump: Negative results are good news. Unfortunately that does not guarantee that the lump is no a problem. Most lumps not seen on these tests are not harmful and either normal fibrous tissue or a normal fat deposit. However the only way to be absolute when a lump is not visualized is to have a biopsy done. I would suggest you discuss this with your doctor and have it rechecked in a month or two.

Lump: Mammography and ultrasound are not 100% sensitive. However, if you have a large palpable lump it would be unlikely that both tests would be normal if it was a large cancer. It is probably normal tissue, but a clinically palpable mass shouldn't be ignored if it feels suspicious. MRI may help in this situation, or you may need biopsy. Talk to your doc about next steps.