I am a 28 years old male with a healthy build up. Last week I found a pea sized lump behind my right nipple. It was very hard and sore when I squeeze it. I had a similar lump in my groin about a month ago, which was later seen disappeared. Is this a symptom of breast cancer? I heard that breast cancer is not so common in men. Or is it some lymph node swelling? But lymph node swellings are not so hard, right? I have checked my blood for confirmation, but ended with no results. Please help.