What is a mass in a muscle at the site of an old injury called?

Answer 1

It depends on the nature of the injury and how old it is. If you had a muscle tear it is probably scar tissue and doesn't necessarily have a name. If you bled into the muscle, you could have a collection of blood called a hematoma. Also the muscle itself can bunch up an create a lump it is complete detached on one end.

Lipoma is a fatty tumor, probably not caused by trauma. A fibroma is a tumor which may occur in site of old injury or surgery, but can also occur spontaneously.

Answer 2

Either a lipoma or a fibroma

Answer 3

Scar tissue, have it removed.