Hi. My girlfriend has a small red scaly spot under
Hello and welcome to 'Ask A Doctor' service,
If she has a history of eczema, this spot could be due to that. It can also be a small fungal infection (yeast or ringworm). Rarely, Paget's disease of the breast can cause what looks like eczema of the nipple. If she just had a mammogram though, that would make this even less likely.
She can try a moisturizer such as Eucerin to see if it will go away. If she needs definitive reassurance, and the Eucerin doesn't help at all, then best to go into her doctor.
I hope this information helps.
Please let me know if I can provide further information or clarification.