Polymyosit is a rare form of arthritis and is defined as a chronic inflammatory, destructive, autoimmune muscle disease that causes muscle weakness and in some cases, pain. In polymyositis the muscle fibers get inflamed. At the beginning of the illness the white blood cells (which are the immune cells of inflammation) suddenly invade those muscles, which are typically close to the trunk (torso). As a result, the patient starts feeling muscle weakness, which can be severe. Within the path of this chronic illness there are „flares“ or „relapses“, which means that progressive muscle weakness is sometimes present and sometimes there are minimal or no symptoms at all (also called „remissions“).

Polymyositis affects women more often than men. It is present in all age groups (specially in the age range between 30's-60's) although its onset is most common in middle childhood and in the 20s. It affects people in all countries but it is more common in blacks than in whites. Due to the fact that polymyositis can affect other body areas it is characterized as a systemic illness. Seldom it is associated with cancer or with other illnesses of connective tissue such as systemic lupus erythematosus, scleroderma and rheumatoid arthritis. Further, Polymyositis is also associated with illnesses such as:

  • Raynaud's phenomenon: Is a condittion in which fingers, toes, cheeks, nose and ears turn pale initially when exposed to cold temperatures.

  • Cardiovascular disease: The muscular walls of the heart can become inflamed due to polymyositis. Further, polymyositis can cause congestive heart failure and heart arrhytmias in few patients.

  • Lung disease: the lung disease „interstitial lung disease“ may happen with polymyositis. This illness refers to a group of disorders that cause fibrosis (scarring) of lung tissue, as a result lungs become stiff and unelastic.


Causes of Polymyositis:

In fact, the cause of polymyositis is unknown but some patients have indicators of genetics suceptibility (heredity). Another possible cause of polymyositis is the infection by an unknown virus -which is resistant to treatment- in a muscle disease called inclusion body myositis. A pathologist can analyse the patient and diagnose this illness by conducting some tests. A further cause of polymyositis found out by researchers is the infection caused by the cytomegalovirus (CMV).

It is important to mention that polymyositis can be confused with other illnesses such as nerve-muscle diseases (e.g. muscular dystrophies), drug toxins (e.g. alcohol, cocaine, steroids, colchicine, hydroxychloroquine and cholesterol-lowering drugs called statins), metabolic disorders (where muscle cells are unable to process chemicals in a normal way), hormone disorders (e.g. abnormal thyroid), inclusion body myositis, calcium and magnesium conditions, and infectious diseases such as influenza virus, HIV, streptococcus and Lyme bacteria, park tapeworm, and schistosomiasis.

Due to the fact that there is no cure for polymyositis, it can be treated with a combination of medications and physical therapy so that muscle strength and function can be improved.