Fat necrosis literally means fat tissue dying. When fat tissue dies, it calcifies and becomes hard. This type of process can produce a lump and even puckering of your breast. It often occurs after sustaining some trauma to the breast which resulted in the fat necrosis. If you have not sustained any trauma, then I do not think I would feel comfortable calling a puckering of the breast just fat necrosis.
The next best step for you depends a lot on your age and family history. If you are young (less than 40), then you will benefit less from a mammogram. This is because younger women have denser breasts which make mammograms more difficult to interpret. You could have this issue with your breast looked at through an ultrasound, and if anything is found, it can either be biopsied or further looked at through MRI
. If you have a family member that developed breast cancer at a young age (less than 50), then you should probably just jump to the MRI.
These are issues you can sort out with your primary care physician
. If this is the doctor
that is not concerned about this issue, then you can probably bring it up with your OBGYN. Between the two of them, you can get this sorted out.