Okay...for a few months now I have noticed a slight discomfort in the mid-section of my left arm whenever I extend it. I haven't really given it much thought until last night. I began massaging the area because of the strange pain there, and not really expecting to feel anything, but I noticed a lump and a knot beneath the skin. The other day, and from time to time, I do lift dumbells (15 pds.). So, now I am wondering if I have just pulled something or is it possibly something more serious like a soft tissue sarcoma?!?