"What's this hard lump on my leg?" A very obese friend of mine has decided to start exercising regularly and eating less to lose weight.  Surprisingly, she's stuck with it for several months and has been making steady progress after decades of indolence. Yesterday she was very concerned about a long, hard lump she discovered on one of her legs and was concerned she had cancer or a tumor since she'd never felt anything hard there before. ...turns out her "tumor" was leg muscle that she hadn't been able to feel in decades.