<s>[INST] I have a lump in the inside of my right upper arm. Swelling and tenderness have been present for over two years. I ve been ultrasound for clots and etc, nothing. What do you think it could be? I also have a small cyst in my left breast. any connections [/INST] Hi, dairy have gone through your question. I can understand your concern.  You have cyst in breast.  It can be some benign cyst or fibrotic disease.  You should go for fine needle aspiration cytology or biopsy of breast cyst.  If ultrasound suggest nothing in your arm then no need to worry. It can be some muscle mass.  There is no relation in between your breast cyst and arm swelling. 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. </s>