Dermatomyositis

Characteristics

Dermatomyositis is a muscle disease characterized by inflammation and weakness, primarily affecting the upper arms and legs. Over time, the respiratory and swallowing muscles may also be affected. The condition is distinct for its accompanying skin inflammation, with characteristic skin abnormalities often seen around the eyes and on the knuckles.

Prevalence and Disease Course

Dermatomyositis affects approximately 3 in 100,000 people and can occur at any age, but it is most common in children aged 5 to 15 and adults in middle age.

Symptoms include:

• Skin abnormalities:
  • Red-blue patches on the knuckles, knees, and elbows, often swollen due to fluid buildup (Gottron’s papules).
  • A widespread reddish discoloration of the skin.
  • A red-violet rash and sometimes swelling around the eyelids.
• Muscle weakness and pain: Often symmetrical, involving the upper arms and legs.
• Swallowing difficulties: Weakness in throat and swallowing muscles may lead to choking or difficulty swallowing.
• General symptoms: Malaise, muscle pain, and sometimes fever.

The disease often starts with skin symptoms, which may appear before or alongside muscle involvement. There is also an increased risk of interstitial lung disease (inflammation of lung tissue), presenting with dry cough or shortness of breath. Adults with dermatomyositis have a heightened risk of developing cancer.

Cause

Dermatomyositis is believed to result from a disrupted immune response. Normally, the immune system targets and removes foreign substances from the body using antibodies and immune cells. In dermatomyositis, the immune system mistakenly attacks blood vessels in the skin and muscles, classifying them as foreign. This makes dermatomyositis an autoimmune disease.

Treatment

Treatment involves the use of prednisone and other immunosuppressive drugs to control inflammation. While these medications can help resolve dermatomyositis, muscle damage caused by inflammation may lead to lasting limitations.

Immunosuppressive medications, though effective, can have significant side effects, requiring careful management and monitoring.

Key Considerations

• Early Diagnosis: Early intervention can reduce long-term damage to muscles and organs.
• Risk Management: Patients, especially adults, should be monitored for associated risks like interstitial lung disease and cancer.
• Tailored Care: Treatment must balance controlling inflammation and minimizing medication side effects.