Dermatomyositis, also called ‘DM’, is a disease of the connective tissue that’s related to polymyositis in the ‘dermatopolymyositis’ family of myositis disorders (another is polymyositis and dermatomyositis).
The cause of dermatomyositis is unknown, but can be the result of viral infection or autoimmune disease. Many of those who suffer from the condition have previously been diagnosed with infectious mononucleosis and/or the Epstein-Barr virus and the condition has been known to overlap with other autoimmune conditions such as lupus or vasculitis.
Signs and Symptoms
The main symptoms of dermatomyositis are a rash followed by symmetric proximal muscle weakness sometimes with pain (the pain can vary between non-existent or minimal or very severe). A patient then might find themselves feeling lethargic or as with ‘flu’ like symptoms. After falling they may find themselves unable to push themselves up again. This might later progress into a more muscle deterioration that can leave the patient paralysed, unable to walk or even swallow foods and liquids. There may also be other systemic upset including fever, malaise, weight loss and arthralgia.
The skin rash will normally also aid diagnosis. One rash is called ‘gottron’s sign’ and is an erythematous rash that is scaly in appearance and symmetrical on the metacarpophalangeal joint (on the finger). At the same time the patient may also get a ‘heliotrope’ or ‘lilac’ rash on their upper eyelids and sometimes lower which can occur simultaneously with swelling and twitching. The Shawl is a flat lesion that can occur across the back and on the back of the neck in the shape of a ‘V’ and this will worsen when under UV light. Erythroderma is a lesion located on the malar are and the forehead, while mechanic’s hands are rough and cracked skin at the tips of the fingers. A combination of these will normally be present as symptoms of the condition and aid with diagnosis.
There is also a danger of cardiac disease and heart attack and this can sometimes be a cause of death. Gastrointestinal ulcers and infections are also sometimes symptoms and these are more common in younger sufferers.
The diagnosis of dermatomyositis will be based on the muscle weekenss and the existence of these rashes, but will be confirmed by muscle biopsy, EMG or blood tests. However only muscle biospy is truly diagnostic.
Dermatomyositis is relatively rare and there are 5-10 cases for every 100,000 individuals. It tends to be more likely between the ages of 45 and 65 and is more rapidly progressing for young adult patients. It can also occur in children however and particularly between the ages of five and fifteen.
Dermatomyositis has no known cure but there are several management techniques, such as exercise therapy to attempt to strengthen the muscles and a range of medications that can control the disease including prednisolone, methotrexate, intravenous immunoglobulin, azathioprine, rituximab, cyclosphamide and others.
There is no cure for dermatomyositis however in most cases it can be controlled for several years and 90% of patients can survive well for several years with the condition and in some cases remission is possible (after several years the fatality rate is around 15% and there is a 20% chance of remission). Before the use of the medications listed above prognosis was very poor. However it can also be fatal and this can also be as an effect of cardiac complications. It is important that treatment begin as soon as possible.