question: I have had a lump in the crook of my arm for some time now, its about the size of half a golf ball and is tender when pushed. It can hurt if i lift heavy weights or even push the swing for my children! I have had an ultra sound scan done and they cant say what it is other then it looks like muscle tissue. I some times get a pins and needles feeling in my hand. I have not knocked it or strained it.