Dermatomyositis
Also known as: DM, Polymyositis with skin involvement
Dermatomyositis is a rare autoimmune disease characterized by muscle inflammation (myositis) and a distinctive skin rash. The condition can affect both adults and children, with varying degrees of severity. The cause is unknown, but it is believed to involve a combination of genetic predisposition and environmental factors. Dermatomyositis can be associated with underlying malignancies, particularly in adults.
Imagine your body is like a garden, and sometimes your immune system, which is supposed to protect you, gets confused and starts attacking your own muscles and skin. This causes a rash and makes your muscles weak. Doctors can give you medicine to calm down your immune system and help you feel better.
Signs & Symptoms
- Characteristic skin rash (Gottron's papules, heliotrope rash)
- Muscle weakness (proximal muscles)
- Fatigue
- Difficulty swallowing (dysphagia)
- Shortness of breath
- Joint pain
- Calcinosis (calcium deposits in muscles or skin)
- Photosensitivity
- Raynaud's phenomenon
Treatment Options
Corticosteroids (e.g., Prednisone)
HIGHLY EFFECTIVEImmunosuppressants (e.g., Methotrexate, Azathioprine, Mycophenolate mofetil)
MODERATELY EFFECTIVEIntravenous Immunoglobulin (IVIG)
MODERATELY EFFECTIVERituximab
MODERATELY EFFECTIVE Approved 2019Physical therapy
SUPPORTIVESpeech therapy
SUPPORTIVEOccupational therapy
SUPPORTIVECalcinosis management (e.g., surgical removal, medications)
SUPPORTIVEDiagnosis
- Physical examination
- Skin biopsy
- Muscle biopsy
- Blood tests (creatine kinase, aldolase, anti-Jo-1 antibodies, anti-Mi-2 antibodies, other myositis-specific antibodies)
- Electromyography (EMG)
- Magnetic resonance imaging (MRI) of muscles
- Cancer screening (age-appropriate)
- Pulmonary function tests
History
Dermatomyositis was first described in the late 19th century. The association with malignancy was recognized in the mid-20th century. Significant advances in understanding the immunopathogenesis and developing targeted therapies have occurred in recent decades.
Recent Breakthroughs
Novel Myositis-Specific Antibodies Identified
Identification of new myositis-specific antibodies that can aid in diagnosis and potentially predict disease phenotype and prognosis.
Targeted Therapies Showing Promise in Refractory Dermatomyositis
Clinical trials evaluating targeted therapies, such as JAK inhibitors and B-cell depleting agents, have shown promising results in patients with refractory dermatomyositis.