Sheila (name changed) suffered the worst itch of her life, which got even worse after she caught the flu some months back. Thinking it was just one of those bothersome rashes, she got some topical shampoos to eliminate them. However the rash only got worse, and so did the itch. It was only when she got to the hospital that it was discovered that she had a rare condition known as dermatomyositis.
Dermatomyositis is an autoimmune disease which belongs to a group of disorders known as Idiopathic Inflammatory Myopathies or Autoimmune Myopathies.
Let's break it down a bit: dermatomyositis is an inflammation of the skin and the muscles as a result of the body's immune system fighting against the body itself.
Subtypes of Dermatomyositis
Classic Dermatomyositis doesn't affect just the skin and muscles; some other systems can be involved such as the cardiovascular, pulmonary and even digestive systems. However there are subtypes that tend to affect just the skin (known as Amyopathic Dermatomyositis) or also show clinical features of muscle damage (known as Clinically Amyopathic Dermatomyositis or CADM). There's also the kind that affects children, known as Juvenile Dermatomyositis.
Good news: this condition is rare!
It has an estimated incidence of 9.63 cases per million population. This means that out of a million people in a given population, approximately 9.63 people come down with dermatomyositis.
Even though all ages can be affected, it occurs more commonly in adults, with a peak age of 50 years. Females are affected more than males with a female-to-male ratio of about 3:1.
Although people of all races can be affected, certain types of dermatomyositis may be more prevalent among certain races.
The Big Question: What Causes Dermatomyositis?
Scientists have the same question. An exact cause of dermatomyositis is yet to be discovered. So far, only theories are available to expose some things that may trigger the condition.
Genetics: Genes account for the variations seen between one individual and the other, and this is not different in dermatomyositis. The presence of some human leukocyte antigen (HLA) types such as DR3, DR5, and DR7 have been shown to confer a predisposition to the development of dermatomyositis.
Immunology: Antibodies are proteins produced by your body to fight infection. In autoimmune conditions like dermatomyositis, the body produces "autoantibodies," which fight against the body itself.
Infections: When some little buggers find their way into one's system they could trigger the condition. These include bacteria like Toxoplasma or Borrelia species and Viruses such as Coxsackie or HIV.
Environmental triggers: These include some drugs (like statins, cyclophosphamide, hydroxyurea among others) stress or a co-existing chronic disease.
When one or more of these factors are present, these autoantibodies destroy the blood capillaries through a series of complex pathways, and cause some of the characteristic symptoms and signs of the disease.
What Are The Characteristic Features of Dermatomyositis?
Remember, the skin, muscles and other systems can be affected.
Features that can be seen on the skin include:
- A heliotrope rash: Purplish or reddish rash around the eyelids and face. It appears in a butterfly-like fashion on the face. There may or may not be an accompanying eyelid swelling.
- Gottron Papules: Wart-like lesions that appear over the small joints of the fingers and sometimes feet. Sometimes, even in the absence of the papules, some scaly, violaceous eruptions may occur over these same joints and this refers to a Gottron sign.
When the Gottron papules and heliotrope rash are present, it's almost certain that the patient has dermatomyositis
- Purplish or reddish rash on the chest (known as a V-neck sign because of the shape it takes) and the upper back regions (known as a shawl sign, considering the area where a shawl drapes over)
- A persistent rash predominantly on other sun-exposed areas: cheeks, nose, back, elbows, knees, and knuckles. This rash doesn't go away even when you use drug-laced shampoos. Worse still, they're photosensitive so they are triggered by sun exposure. Itching typically accompanies the rash, and it can be severe enough to disrupt sleep or daily activities. Research is still ongoing on drugs to specifically target the itching.
- Calcinosis: As a result of muscle breakdown, calcium salts are deposited underneath the skin and within muscles. They often appear as whitish or yellowish swellings on the skin.
- Scaly scalp and hair loss.
Features indicating muscle involvement include:
- Progressive muscle weakness, evidenced by one or more:
- inability to hold up the hands for long
- difficulty with combing the hair
- difficulty with climbing stairs or getting up from a seated position.
- Muscle pain
- Quadriparesis (weakness of all four limbs at once) in some cases
Features indicating systemic involvement include:
- General features: Fever, general weakness, joint pain, weight loss, Raynaud phenomenon. Raynaud phenomenon is the response certain body parts (like the fingers, toes, ears and tip of the nose) give to cold temperatures or stress, as a result of spasms of the blood vessels supplying them. These body parts usually change colour: first white, then blue, then red.
- Difficulty in swallowing (dysphagia) and acid reflux
- Voice changes, as a result of involvement of the muscles that control phonation
- Heart disorders such as arrhythmias and heart muscle defects (cardiomyopathies)
- Respiratory disorders such as shortness of breath and interstitial lung disease
- Malignancy, more commonly in adults.
How is Dermatomyositis Diagnosed?
A high index of suspicion is considered when you have a family history of dermatomyositis, suggestive symptoms, and signs elicited during a thorough physical examination. This diagnosis is further confirmed by specific laboratory investigations, imaging studies and histological studies.
The tests are numerous, and so your rheumatologist would advise on the exact tests you as an individual require.
Can Dermatomyositis be Cured?
Dermatomyositis doesn't have a cure, but it can be properly managed to give you the best quality of life possible.
Lifestyle changes:
- Use broad-spectrum sunscreens and sun-protective clothing.
- Avoid the sun as often as you can.
- Elevate the head of your bed or sleeping on double pillows, especially if you're experiencing shortness of breath or heart issues.
- Modify your diet (for instance, change from solids to semi-solids or fluid meals) to combat dysphagia.
Use of Medications:
Drugs such as corticosteroids, immunosuppressants, immune globulins, as well antimalarial agents have been shown to be helpful in the management of dermatomyositis. However, these drugs should only be obtained with a doctor's prescription.
Surgery is not necessary in the management of dermatomyositis, except in severe cases of calcinosis.
Some complications you should know about
- Malignancy has been known to complicate dermatomyositis, especially in adults. They include ovarian, prostate, lung, pancreatic, breast, nasopharyngeal and haematologic cancers.
- Joint contractures, which causes stiffness and deformity in the joints, can occur in children due to calcinosis.
- Other systemic complications such as heart and lung disease, venous thromboembolism, osteoporosis, et cetera.
Prognosis: What Determines how Severe a case of Dermatomyositis can be?
In up to 20% of cases, spontaneous remission has been observed while about 5% progress to more severe disease and eventual death.
Generally, patients older than 60, those with malignancy, children with contractures, and patients of lower socioeconomic (who often experience a delay in diagnosis and institution of therapy) tend to have a poorer prognosis than their counterparts.
Some Other Conditions that may Mimic Dermatomyositis
- Lupus: The rash in dermatomyositis is similar to that of lupus, except that it doesn't spare any area of the face unlike lupus. A typical lupus rash spares the nasolabial folds of the face. Nasolabial folds are the lines that run from the lower part of the nose to the corners of the mouth.
- Other types of autoimmune muscle disease such as Polymyositis, and other inflammatory myositis.
In summary: What happened to Sheila?
Sheila sought medical care and she's doing much better now. The rash and the accompanying itch have reduced drastically, and she feels good about herself again.
Because this condition is relatively rare, it is not talked about very often. However there are real people living with it. If you think you may have dermatomyositis, be like Sheila: visit your dermatologist or rheumatologist so that you can be treated quickly and properly.
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Images were obtained from Wikimedia.