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Understanding causes

Dermatomyositis is an inflammation of the striated muscles (myositis) involving the skin and internal organs such as kidneys, lungs and heart. In this rheumatoid inflammatory autoimmune disease, the body's own immune system attacks parts of the muscles and skin. However, if only the muscles are affected, this is referred to as polymyositis.

The reasons for this disease are still unclear. The disease often occurs in connection with a malignant tumour. To what extent a genetic disposition is decisive for the outbreak of the disease or pathogen (such as viruses, bacteria or toxoplasms) is just as unclear as whether disturbances of the cell-mediated immune reaction or autoantibodies can trigger the disease.

Facts and figures around the disease

Dermamyositis is a rare disease that can occur at almost any age and affects more women than men. There are two age phases in which most new diseases are recorded:
1. In childhood (Juvenile Dermamyositis)
2. In middle age between 45 and 60 years of age

Typical symptoms and course of the disease at a glance

The disease usually occurs insidiously within 3 to 6 months. In addition to general signs of the disease such as fatigue, weight loss and fever, there are cases of rhabdomyolysis, dissolution of the striated muscles or myoglonimuria, i.e. increased excretion of myoglobin via the urine due to injuries of the striated muscles.

Both forms of the disease cause muscle weakness of the large thigh and upper arm/shoulder muscles. The swallowing apparatus and other muscle groups can also be affected. In the case of dermatomyositis, the disease can also manifest itself in a lilac reddening of the skin. Preferably in body parts that are frequently exposed to the sun, such as eyelids, bridge of nose, cheeks, décolleté and the extensor sides of the hands.

Different manifestations:

  • Erythematous dermatitis: reddish scaly papules (skin nodules) mainly over the back of the hand, over the base and middle joints of fingers and knee joints, elbows, inner ankles, face, neck and upper trunk
  • Facies myopathica: combination of skin changes and a mimic rigidity (sad, wimpy, desperate facial expression)
  • Wine-red livid erythema on the shoulders, back and upper arm extensor sides
  • Further signs: telangiectasias (expansion of superficial small blood vessels), atrophies (tissue loss), ulcerations (circulatory disorders), scaling, pigment shifts, scleroderma-like hardening, rough skin
  • Calcifications of the skin
  • pulmonary fibrosis

How does the physician make the diagnosis?

  • Clinical examination of the skin changes
  • Measurement of muscle activity by electromyographic examination
  • Determination of inflammation parameters
  • Determination of autoantibodies
  • Use of imaging techniques: X-ray, sonography, computer tomography or magnetic resonance tomography
  • Muscle biopsy

How is dermamyositis treated?

Due to the rarity of the disease, there are no standard therapies available so far. Therefore, an individual plan must always be drawn up for drug treatment.

  • The remedies of choice are glucocorticoids
  • Immunoglobulins
  • Various immunosuppressants, including methotrexate and azathioprine

Practical tips for everyday life

In case of new muscle weakness or skin changes described above, a rheumatologist or neurologist should be consulted immediately.