Both Polymyositis and dermatomyositis have symptoms in common with sclerosis or sometimes lupus.
Signs of these conditions may appear suddenly and severely or gradually and more mildly. Symptoms are more likely to be gradual in older people. Sometimes a person may have a serious infection before the symptoms begin.
The symptoms include:
- Muscle weakness. This is usually not noticeable until the disease is advanced and about half the muscle fibers have been destroyed. A person may have difficulty raising his or her arms above the shoulders, climbing steps or rising from sitting. If the neck muscles are seriously affected, it may not be possible for the person to lift his or her head from the pillow. If the muscles of the throat are affected, the person may have difficult using his or her voice.
- Contraction of the arms and legs. While the hands, feet and face are usually not affected by this condition, the arms and legs may tighten up in the late stages of the disease.
- Shortness of breath. This is caused by gradual damage and weakness of the chest wall and the muscles that move the diaphragm during breathing.
- Difficulty swallowing. This may occur when the muscles of the throat and esophagus (the tube that connects the mouth to the stomach) are involved
- Muscle tenderness or pain
- Raynaud's phenomenon
- Feeling tired
- Weight loss
Compared to lupus or sclerosis, there is relatively little organ involvement with polymyositis. Sometimes, however, the effect on specific organs may be the first symptoms. These include breathing problems, heart disorders involving irregular rhythms or electrical signals, kidney failure or digestive tract ulcers.
If dermatomyositis occurs along with polymyositis, symptoms may also include:
- Skin rash. This can be either raised and smooth or scaly. It may appear on the forehead, the neck, shoulders, chest and back, forearms and lower legs, elbows and knees or the joints of the fingers, toes, wrists and ankles.
- Swelling around the eye. This may look purplish and bruised.
- Swelling at the base and sides of the fingernails
- Splitting of the skin of the fingers
While the skin eruptions often completely fade away, some leave behind brownish spots, scars or smooth white patches.
Causes and Risk Factors
It is not known what causes these conditions. It may be an immune reaction of the body against its own tissues. Viruses may play a role. A tumor may spark an immune reaction against both tumor and the muscle tissue.
Polymyositis and dermatomyositis occur almost two times often in women than men.
While it can occur at any age, it usually appears in people between the ages of five to 15 or 40 to 60.