Hello, this seems like a type of fibromyositis, which often accompanies degenerative arthritis. Do you also have any form of arthritis, like Rheumatoid or gout?
Is the torn muscle mass tender to the touch or painful? Does it restrict your hand movements significantly?
A lot would depend upon the answers to these questions, because they would indicate whether the condition is due to a degenerative condition or no.
Also, what is the name of the probable disease your doctor told you? I'd like to know that!