<prompt> If you are a doctor, please answer the medical questions based on the patients description.I am really worried about this small hard lump on my left mastoid process. It doesn t hurt until you press it. Its been there for quite a long time. I even clicked a picture of it if you might need to see it for reference. I am very scared. I am just nineteen , what could possibly be the reason for it. Please help.  <response>: Hi, dear. I have gone through your question. I can understand your concern. You may have some reactive lymph node due to infection in that region. Or you may have mastitis. Just take a course of antibiotics. If lump doesnt respond to treatment then biopsy diagnosis is advisable. Consult your doctor and take treatment accordingly. Hope I have answered your question, if you have doubt then I will be happy to answer. Thanks for using Chat Doctor. Wish you a very good health. 