Polymyositis is a disease of the muscles. It usually affects the
muscles closest to the trunk of the body. However, it may affect
muscles anywhere in the body. The muscles become inflamed or
swollen. This causes pain. The disease is progressive and starts
slowly. If untreated, the muscles gradually become weaker. The
pain in the muscles also increases. Front Muscles of Trunk
Copyright © Nucleus Medical Media, Inc. This rare disease is
believed to be an autoimmune disorder. Your immune system is
your body’s defense system. It fights diseases and infections.
In this case your immune system attacks your own muscle tissue
by mistake. The sooner the disease is treated, the better the
outcome. If you suspect you have this condition, contact your
doctor. The cause is unknown. Factors that may contribute to
polymyositis include: - A virus that sets off the condition - A
reaction to certain drugs that set off the condition Risk
Factors TOP The following factors increase your chance of
developing polymyositis: 50-70 ye