Hi,
An Intramammary lymph node is not uncommon,.and means nothing unless it were noted to be abnormally enlarged or looks suspicious on film produced by radiography.
An enlarged lymph node also in the axilla area, doesn't necessarily mean it's something serious.Usually when there is an infection or inflammation somewhere in the body,a lymph node may enlarge and may remain enlarged for quite a long time.
I don't think you have reasons to worry,but please see your doctor for evaluation and I am sure that he/she will discuss with you if the lymph nodes need to be further investigated or just monitored to make sure that they do not become abnormally enlarged.
Take care and best wishes....