Dermatomyositis

Synonyms

Dermatopolymyositis, idiopathic inflammatory myopathy , Polymyositis with skin involvement,

Overview

Dermatomyositis is a rare autoimmune disease that causes inflammation, leading to a characteristic skin rash and progressive muscle weakness. Symptoms can include a distinctive reddish-purple rash, especially on the eyelids and joints, and symmetric weakness of the proximal muscles. While treatments like corticosteroids and physical therapy can manage symptoms, there is currently no cure for the condition. It can also affect other organs like the lungs and is associated with a higher risk of underlying malignancy.

Symptoms

Dermatomyositis symptoms include progressive muscle weakness in the shoulders, hips, and neck, along with skin rashes like a violet rash on the eyelids (heliotrope rash) and red bumps on the knuckles (Gottron’s papules). Other common symptoms are difficulty swallowing, shortness of breath, weight loss, and fatigue.

Causes

The exact cause of dermatomyositis is unknown, but it is an autoimmune disease where the immune system attacks the body’s own muscles and skin blood vessels. Experts believe a combination of genetic, environmental, and immunologic factors may be involved. Potential triggers include viral infections, exposure to certain medications, and sun exposure. Some people with dermatomyositis also have or are at higher risk of developing certain cancers, particularly in the abdomen, lung, and other parts of the body. 

Prevention

Dermatomyositis cannot be entirely prevented because its exact cause is unknown, but proactive steps can help manage symptoms and reduce flare-ups. Key preventative strategies include sun protection by using sunscreen and wearing protective clothing due to the condition’s photosensitivity, and engaging in regular, low-impact exercise to maintain muscle strength and flexibility. Following a healthy, balanced diet and adhering to prescribed medication and routine medical check-ups also helps in managing the condition and preventing complications.

Diagnosis

Dermatomyositis is diagnosed by a healthcare professional through a physical exam, checking for a characteristic skin rash and muscle weakness, along with a combination of tests including blood work (for muscle enzymes and autoantibodies), imaging (MRI, chest X-ray), electromyography (EMG), and skin or muscle biopsies to confirm inflammation and damage.

Prognosis

Dermatomyositis prognosis varies, but with early diagnosis and treatment, many people go into remission or achieve long-term symptom management, improving quality of life. Factors associated with a poorer outlook include delayed treatment, severe muscle weakness, dysphagia, respiratory muscle weakness, interstitial lung disease, cardiac involvement, and underlying malignancy. While it’s not typically fatal with proper management, the disease can be chronic, with symptoms lasting for years or resolving completely in some cases.

Treatment

Dermatomyositis treatment aims to reduce inflammation and improve muscle strength and skin issues, as there is no cure. Key treatments include corticosteroids, immunosuppressant drugs (like methotrexate and mycophenolate mofetil), and intravenous immunoglobulin (IVIg) infusions. Other therapies include physical therapy, sun protection, and, in some cases, topical treatments and speech therapy.