Dermatomyositis Symptoms

Skin changes in Dermatomyositis (Click for a larger image)

Dermatomyositis is an inflammatory disease of muscles and skin, which causes muscle weakness and a very reddish or even purplish rash across the face, chest fingers and neck.  This weakness usually develops slowly over weeks to months although rare cases can begin over days. This weakness most commonly affects the muscles of the arms and legs. Patients often notice trouble getting out of chairs or climbing stairs. It does not typically involve the muscles of the eyes, heart, or breathing muscles. However the muscles involved in swallowing can become weak as well.  Muscle pain may also be a prominent symptom since dermatomyositis is associated with inflammation in the muscles. The rash can look very similar to a number of other rash types and by skin biopsy there is nothing that distinguishes dermatomyositis from a host of other skin rashes.  Clinically the appearance if often quite characteristic to neurologists, rheumatologists, and dermatologists.

Nailfold Lesions

The diagnosis of dermatomyositis begins with a neurologist taking the patient's history and performing a clinical exam, especially examining the rashes. A physician who suspects a diagnosis of dermatomyositis may perform blood tests, an EMG, or a magnetic resonance imaging scan (MRI).  The blood tests reveal elevated levels of enzymes which are found in muscle.  Doctors may check a creatine phoshpokinase (CPK) or an aldolase.  Without elevated levels of one of these enzymes it is very unlikey to have a diagnosis of dermatomyositis.  The EMG test looks at the function of a patient’s muscles and will reveal evidence for muscle inflammation and muscle damage.  An MRI looks for visual evidence for inflammation in a group of muscles. It can also be used to choose which muscle to biopsy. 

Gottron's Papules

If these three non-invasive tests suggest a diagnosis of dermatomyositis then patients should have a muscle biopsy before beginning therapy. A muscle biopsy is needed in all patients for a definitive diagnosis.  Finally there are a very specific set of blood tests called Myositis Specific Autoantibodies. These antibodies are found in 20-30% of patients with dermatomyositis but are important because they can predict the presence of other associated conditions.

Causes of Dermatomyositis
Cure for Dermatomyositis
Dermatomyositis Treatment
Dermatomyositis Research