Dermatomyositis: Causes, Symptoms, and Treatment

Dermatomyositis or DM is a disease of the connective-tissue which is characterized by inflammation of the skin and muscles. This condition affects adults and children alike, however it is more prevalent in women then men. It mostly affects the skin and muscles, but it may also affect the lungs and esophagus.

Paraneoplastic is a phenomenon that develops in the presence of cancer, usually pre-existent ones. In such cases, the removal of the cancerous growth results in dermatomyositis remission. The condition, on diagnosis, discloses dystrophic calcification of muscles and sometimes calcium deposits under the skin.

The accompanying rash appears and disappears with topical applications, but the Gottron's papules, pink knuckle patches, and priapism are unmistakable symptoms. This malady is studied in relation to polymyositis and body myositis. When the condition strikes children, it is referred to as juvenile dermatomyositis (JDM).

Though the cause for the onset of dermatomyositis remains unknown, research reveals that it could be associated with a viral infection or some autoimmune reaction. There have been a number of cases in which the condition has developed in the presence of autoimmune diseases such as scleroderma, lupus, or vasculitis.

The link between dermatomyositis and autoimmune disease has been established beyond doubt and is the main reason for the preference of antinuclear antibody tests for proper diagnosis.

The main signs and symptoms include:

• Skin rash
• Symmetric proximal muscle weakness
• Muscle pain
• Temporary paralysis
• Difficulty in swallowing
• Scaly skin eruption
• Flat, erythematous lesion on the shoulders and chest
• Periungual telangiectasias
• Erythema
• Psoriasiform scalp changes
• Gastrointestinal infection
• Lung problems

In this condition following abnormalities are observed:

• Muscle fascicles, surrounded by shrunken polygonal muscle fibers
• Mature lymphocytes, with scant cytoplasm and dark nuclei
• B- and T-cells in equal numbers
• Damaged microscopic vessels and lymphocytic inflammation
• Tissue ischemia
• Dominant lymphocyte myopathies, inflammatory in nature

This condition can be treated with the help of prednisone, plasmapheresis, IVIG (intravenous immunoglobulin), and chemotherapy. Today, there are a number of immune-modulating drugs available to address the onset of this condition.

Before the treatment, a thorough diagnosis of the condition with the help of EMG (electromyography), muscle biopsy, and a number of other prescribed blood tests is done. The muscle biopsy results usually highlight either mixed B and T-cell perivascular infiltrate or perifascicular muscle atrophy.

The condition is commonly associated with auto-antibodies like anti-Jo1. Dermatomyositis is also treated with the help of orthotic devices. Options like intravenous immunoglobulin, immunosuppressants, and topical corticosteroids are a part and parcel of the treatment package.

Corticosteroids help to suppress the immune system and limit antibody production. This helps in reducing the painful muscle and skin inflammation. However, prolonged corticosteroid usage results in osteoporosis, weight gain, and diabetes.

The immunosuppressant treatment option includes the administration of drugs such as azathioprine and methotrexate. Antimalarial medication like hydroxychloroquine and chloroquine phosphate also helps to ease the inflammation. Physical therapy is also an important part of treatment. 

The exercises are designed around the need to improve muscle strength and flexibility. Surgery is a treatment option resorted only to remove the painful calcium deposits. Doctors may also prescribe pain relievers and radiation therapy.

Research is being conducted to explore gene expression patterns typically seen within inflammatory myopathies. Scientists are now considering the role of viral infection as an indicator of the disorder. The condition is triggered when the immune system is unable to effectively protect healthy cells from attacks by bacteria and viruses.

The produced autoimmune antibodies or autoantibodies end up attacking the body's tissues and the inflammatory cells then lead to degeneration of muscle fiber. Dermatomyositis can occur at any age, but is most commonly observed in the age groups 5-15 and 40-60. The condition develops over a period of several months.

The condition worsens during pregnancy and increases the risk of premature and/or stillbirth. Once diagnosed, it is important to adhere to the adopted treatment plan prescribed by the doctor. This helps to improve skin texture and muscle strength.