My DH has a lump on the back of his thigh that is hard and about 5cmx3cm. He noticed it the other day, and as he does a lot of running, we thought it must be something to do with that. He had a physio appointment today and they said they don't know what it is and are sending him for an ultrasound. I have stupidly googled, and am now terrified that he has a sarcoma. Please tell me it could be something harmless!