Dermatomyositis
An inflammatory disease causing muscle weakness and a skin rash
Quick Facts
- Type: Inflammatory autoimmune disease
- Main features: Muscle weakness and a distinctive skin rash
- Who it affects: Adults and children, more often females
- Mainstay of treatment: Corticosteroids and immune-suppressing drugs
Overview
Dermatomyositis is a rare inflammatory disease that affects both the muscles and the skin. It belongs to a group of conditions called inflammatory myopathies, in which the immune system mistakenly attacks the body's own tissues. The hallmark of dermatomyositis is muscle weakness combined with a characteristic skin rash, which often appears before or alongside the muscle symptoms.
The condition can occur in both adults and children, and it affects women more often than men. Although there is no cure, treatment can control inflammation, improve muscle strength, and clear the rash for many people. Because dermatomyositis can occasionally be linked to other conditions and, in adults, to an underlying cancer, careful evaluation and ongoing follow-up are important.
Symptoms
Dermatomyositis typically causes a combination of skin and muscle symptoms that often develop gradually over weeks to months.
- Skin rash: a reddish or purplish rash, often on the eyelids, face, knuckles, elbows, knees, chest, and back
- Muscle weakness: usually affecting muscles closest to the trunk, such as the hips, thighs, shoulders, and neck, making it hard to climb stairs, lift objects, or rise from a chair
- Difficulty swallowing or a hoarse voice
- Fatigue and general tiredness
- Muscle pain or tenderness
- Hardened calcium deposits under the skin, more common in children
Some people develop lung or joint involvement, and the rash can be sensitive to sunlight.
Causes
The exact cause of dermatomyositis is not fully understood, but it is considered an autoimmune disease in which the immune system attacks the small blood vessels in muscles and skin.
- Immune system malfunction: the body produces antibodies and immune cells that damage muscle and skin tissue.
- Genetic tendency: certain inherited factors may make some people more susceptible.
- Possible triggers: infections, sunlight, certain medications, and, in some adults, an underlying cancer may play a role in starting or worsening the disease.
It is not contagious and is not caused by anything a person did or ate.
Risk Factors
- Female sex, as the condition is more common in women
- Certain age groups, with peaks in childhood and in middle-aged adults
- A personal or family history of autoimmune disease
- In adults, an associated underlying cancer in some cases
- Sun exposure, which can worsen the skin rash
Diagnosis
Doctors diagnose dermatomyositis using a combination of the typical rash, muscle weakness, and supporting tests.
- Physical examination: recognizing the characteristic skin rash and pattern of muscle weakness.
- Blood tests: muscle enzymes such as creatine kinase are often raised, and specific autoantibodies may be present.
- Electromyography (EMG): measures the electrical activity of muscles.
- MRI: can show muscle inflammation and guide where to biopsy.
- Muscle or skin biopsy: a small sample examined under a microscope confirms the diagnosis.
- Cancer screening: adults may be evaluated for an underlying cancer, as dermatomyositis can sometimes be associated with one.
Treatment
There is no cure, but treatment can control the disease and restore much function. Care is usually guided by a rheumatologist, often with a dermatologist.
- Corticosteroids: such as prednisone, are the first-line treatment to reduce inflammation quickly, then tapered to the lowest effective dose.
- Immune-suppressing medications: added to control the disease and allow steroid doses to be lowered.
- Intravenous immunoglobulin (IVIG): used in some cases to calm the immune attack.
- Physical therapy: exercise to maintain and rebuild muscle strength and flexibility.
- Skin care and sun protection: sunscreen, protective clothing, and topical treatments for the rash.
- Treating associated conditions: managing lung involvement or an underlying cancer when present.
Prevention
Dermatomyositis cannot be prevented, but steps can reduce flares and complications once it is diagnosed.
- Take medications exactly as prescribed and attend regular follow-up visits
- Protect skin from the sun with sunscreen and protective clothing
- Stay active with a physical therapy or exercise program to preserve strength
- Report new symptoms, infections, or medication side effects promptly
- Keep up with recommended cancer screening as advised by your doctor
When to See a Doctor
See a doctor if you develop progressive muscle weakness, especially in the hips, thighs, shoulders, or neck, or an unexplained reddish-purple rash. Seek prompt or emergency care for:
- Difficulty swallowing or choking on food
- Shortness of breath or a new cough, which can signal lung involvement
- Weakness severe enough to cause falls or trouble breathing
- Signs of serious infection while taking immune-suppressing medication
Frequently Asked Questions
What is dermatomyositis?
Dermatomyositis is a rare inflammatory disease in which the immune system attacks the muscles and skin. It causes muscle weakness, especially around the hips and shoulders, together with a distinctive reddish-purple skin rash. It can affect both children and adults.
Is dermatomyositis linked to cancer?
In some adults, dermatomyositis is associated with an underlying cancer, so doctors often recommend cancer screening after diagnosis. This link is much less common in children. Regular follow-up helps detect any associated condition early.
Can dermatomyositis be cured?
There is no cure, but the disease can usually be controlled with treatment. Corticosteroids and immune-suppressing medications reduce inflammation, improve muscle strength, and clear the rash for many people, often allowing a return to normal activities.
What does the dermatomyositis rash look like?
The rash is typically reddish or purplish and commonly appears on the eyelids, face, knuckles, elbows, knees, chest, and back. It can be sensitive to sunlight. The rash often appears before or at the same time as muscle weakness.
When should I seek urgent care with dermatomyositis?
Seek prompt care for difficulty swallowing or choking, shortness of breath or a new cough that may signal lung involvement, weakness causing falls, or signs of serious infection while on immune-suppressing medication.
References
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Myositis.
- MedlinePlus, U.S. National Library of Medicine. Dermatomyositis.
- Mayo Clinic. Dermatomyositis — Symptoms and causes.
- National Organization for Rare Disorders (NORD). Dermatomyositis.