Dermatomyositis is a rare muscle disease that causes inflammation of the muscles, skin, and blood vessels. It may also affect other organs, such as the heart and lungs.
Dermatomyositis belongs to a rare group of conditions called inflammatory myopathies. These conditions share certain symptoms, including:
The symptoms vary widely from person to person, but it is generally possible to manage them with treatment.
In this article, we discuss dermatomyositis in detail, including the causes, risk factors, symptoms, diagnosis, treatment, and potential complications.
We also look at the outlook for people with dermatomyositis and explain how this disease differs from other health conditions.
Dermatomyositis is a rare acquired muscle condition, with an incidence of 9.63 per 1 million people. The condition affects females twice as often as males.
All inflammatory myopathies affect the muscles. Dermatomyositis causes weakness of the proximal muscles, which are those near the trunk. It may also affect other parts of the body, including the:
The symptoms of dermatomyositis may be acute, appearing suddenly, or insidious, developing gradually.
Muscle weakness is the
It often affects muscles in the:
- upper arms
The symptoms may lead to difficulty carrying out certain activities, including:
- combing the hair
- lifting the arms
- climbing steps
- getting up from the floor
- raising the head from the pillow
Other muscle groups
The condition may also affect other muscle groups, such as the throat, tongue, chest, and heart. This can lead to:
- difficulty swallowing, known as dysphagia
- difficulty speaking, or dysphonia
- breathing difficulties
- arrhythmia, which refers to abnormal heart rhythms
- heart muscle weakness, or cardiomyopathy
Gottron’s papules are reddish or violet bumps that appear on the surface of bony prominences such as the knuckles, elbows, and knees. A heliotrope rash is a patchy, uneven rash on the upper eyelids.
Other possible skin changes
- reddish purple scaling patches
- poikiloderma, in which the skin has finely mottled areas of hypopigmentation alongside:
- a discolored scaly scalp
- nail bed changes
Other symptoms and associated conditions may include:
The symptoms associated with childhood dermatomyositis are the same as those of adult dermatomyositis, but the onset is more sudden, and the condition often presents with skin changes before muscle weakness.
Widespread blood vessel inflammation, called vasculitis, and calcinosis — large calcium deposits under the skin — occur more frequently in children than in adults. Those affected may also develop a tiptoe gait secondary to ankle stiffness.
However, unlike in the adult form, children with the condition are not at risk of cancer.
Dermatomyositis sine myositis, which doctors also call amyopathic dermatomyositis, is another form of dermatomyositis. It presents with the typical skin lesions of dermatomyositis but without the associated muscle abnormalities.
The cause of dermatomyositis remains unknown, but experts believe that a
- immune system
People with particular human leukocyte antigen (HLA) types are at a higher risk of the condition.
HLAs are proteins that play a role in the body’s immune system.
People with dermatomyositis show an abnormal immune reaction, whereby the body’s immune system attacks small blood vessels, causing inflammatory changes in the:
- blood vessels
Experts have also suggested that certain viruses could trigger the condition. These include:
- Coxsackie B virus
Certain drugs can also trigger dermatomyositis. These include:
Silicone breast implants or collagen insertions may also trigger or worsen the condition.
Dermatomyositis can increase a person’s risk of other conditions:
Weakness and inflammation of the heart muscle can lead to:
Connective tissue diseases
Dermatomyositis can occur together with other connective tissue diseases, such as:
This condition causes the sudden contraction of blood vessels in the hands and toes.
The resulting interruption of blood flow can lead to:
- discoloration of digits
Many people with dermatomyositis also have an underlying malignancy.
Malignancies occur in
Doctors begin the diagnosis by looking at the person’s history, performing a thorough clinical examination, asking the person about their symptoms, and running different tests. Tests that they may request
- blood tests to check muscle enzymes such as creatine kinase and aldolase
- blood tests to check for antibodies, including myositis-specific autoantibodies
- electromyography to identify which muscle groups are most affected
- muscle and skin biopsy
- MRI scans
- barium swallow
- cancer screening, which may involve:
The goal of treatment is to manage specific symptoms and address any other complications.
- Glucocorticoids: This is the first-line treatment for dermatomyositis. Glucocorticoids, particularly prednisolone, help reduce inflammation and swelling and suppress the body’s immune responses. Doctors initially prescribe a high dosage and then taper the drug slowly as the person’s muscle enzyme levels decline.
- Immunosuppressive medications: Doctors may also give other immunosuppressive drugs, such as methotrexate and azathioprine, to those with an insufficient response to steroids alone.
- Intravenous immunoglobulin (IVIG): Doctors may give people who are resistant to steroids IVIG, which they administer directly into the bloodstream. These blood products help boost the body’s immune system.
- Calcium channel blockers: These drugs remove calcium deposits and reduce the effects they may cause on the body.
- Calcification surgery: Surgical procedures can remove calcium deposits that are infected or painful.
- Physical therapy: This therapy improves muscle strength and prevents contractures.
- Speech therapy: This type of therapy helps people manage swallowing and speech difficulties.
Other nonmedicinal management approaches may include:
There is no cure for dermatomyositis. The symptoms may come and go, and a person may require treatment for the rest of their life.
- ischemic heart disease
- pulmonary complications
However, more than half of those who survive retain their usual level of strength, and 16% have no disability. With treatment, 1 in 5 people reach remission, while the rest continue with a polycyclic course.
Dermatomyositis shares some similarities with other muscle and skin conditions, so doctors will need to consider the differences between these conditions when making a diagnosis.
Dermatomyositis vs. polymyositis
Polymyositis is another inflammatory myopathy that causes muscle swelling, tenderness, and weakness.
However, unlike dermatomyositis, polymyositis does not cause skin rashes.
Dermatomyositis vs. lupus
Dermatomyositis affects the joint surface but not the interjoint spaces. However, people with cutaneous lupus have rashes in interjoint spaces.
A scaly scalp is uncommon for people with cutaneous lupus, which does not usually involve the lower extremities.
Dermatomyositis vs. inclusion body myositis
Inclusion body myositis produces symptoms similar to those of dermatomyositis, but it affects different muscle groups. For example, inclusion body myositis affects the wrists and fingers.
Dermatomyositis vs. scleroderma
Scleroderma causes the excessive formation and accumulation of collagen. This condition results in skin thickening and hardening of the skin and specific organs. Scleroderma can occur with dermatomyositis.
Dermatomyositis is a rare muscular condition that requires lifelong treatment. This condition may lead to other health complications, affecting various body parts, such as the skin, lungs, and heart.
A person should work with their doctor to create an effective treatment plan and prepare for possible complications.