I am 47yrs, good health. i never get spots but 2/3 weeks ago ulcer appeared under left breast is it almost certainly breast cancer? straight answer pse

Breast cancer: You need to get a biopsy. There is no plan without a diagnosis. You need the tissue diagnosis.

See your MD ASAP: It is not possible to tell what is going on from your description. You will need to have a history and physical exam and likely a mammogram if you have not had one. You md will decide if it is something limited to the skin or something directly involving the breast. This should not wait go to you md asap.

Straight answer:: Cannot tell for sure without a proper evaluation. Do not freak out, just go see your doc as soon as you can and take it from there, ok? I truly hope you have nothing serious.

See your Surgeon: Developing a rash is more common than an ulcer. And usually breast cancers will start as a lump in the breast tissue and not as an ulcer on the skin. As we are essentially guessing without the benefit of a proper history or an examination therefore the likely diagnosis would be benign but please go and see our pcp or breast surgeon soon so that they can assess you and give you appropriate advice.