My 12 yr old son has a solid nodule behind his nipple. I am concerned.

My 12 year old son showed me a solid nodule behind his nipple.  It is hard to the touch and is under his right nipple.  He said it has been there about 2 weeks.  It hurts to "flex" his muscles.  Is this normal for a boy or should I see his pediatrician asap?
Thank you.

[CCF-RN,MSN-JS]

Dear Hovank, What your son is feeling is most likely from a benign (non-cancerous)cause.  Male breast cancer is rare, but one out of every 150 cases of breast cancer involves a man, usually in men over 60 years old.  Although a painless breast lump is the most common sign, most breast lumps in men are benign (non-cancerous) and are related to some other cause.  The first step in determining what the cause might be in your situation would be to have it examined by your pediatrician.