Dermatomyositis
What is
it?
Dermatomyositis may occur with a disorder called
polymyositis, which affects the muscles, causing
inflammation and weakness. Dermatomyositis includes
these symptoms, as well as skin inflammation.
Who gets
it?
Dermatomyositis can affect any age group, but is more
likely to occur in middle-aged adults. In children, it
usually appears between the ages of 5 and 15. It is
twice as common in women.
What
causes it?
The cause
of dermatomyositis is unknown. It may be related to an
autoimmune reaction, or may be triggered by a virus or
cancer.
What are
the symptoms?
Symptoms of
dermatomyositis usually begin gradually, with muscle
weakness, joint pain, fever, weight loss, and fatigue.
Children may experience a more rapid onset. Muscle
weakness usually affects the upper arms, neck, and
legs, on both sides of the body. Some people
experience joint and muscle pain, and some have
difficulty swallowing. As the disease progresses, the
muscles begin to waste away (atrophy) and permanently
shorten (contracture). A grayish-red rash appears at
the same time as the muscle weakness. The rash
commonly appears on the face and includes a purplish
swelling, called a heliotrope, around the eyes. There
may be a shawl-like rash over the neck, shoulders, and
upper chest and back. Another rash often appears
around the joints, especially around the fingers. This
rash may be smooth or have scaly patches, and is
called Gottron’s sign. When the rash fades, it leaves
behind pigmented patches of skin. Some people with
dermatomyositis develop a rash without muscle
weakness. This is called dermatomyositis sine myositis.
Others may also have Raynaud’s phenomenon, in which
the small arteries in the fingers and toes constrict,
causing the skin to look pale or bluish, usually after
exposure to cold. People with dermatomyositis are more
likely to develop malignant cancers.
How is it
diagnosed?
Dermatomyositis is diagnosed through a thorough
physical exam and the characteristic symptoms. Your
doctor will order diagnostic tests to check levels of
certain enzymes in your bloodstream. He or she will
also take a small sample of tissue from the affected
muscle, called a muscle biopsy, to check for
abnormalities. A test called electromyography will
reveal any abnormal electrical activity in the
muscles. Magnetic resonance imaging (MRI) is also
helpful in revealing muscle inflammation. Your doctor
will order blood tests and other cancer screening
tests to check for malignancies.
What is
the treatment?
The first
line of treatment for dermatomyositis is restricted
activity and a daily injection of a corticosteroid,
such as prednisone, to reduce inflammation and relieve
pain. This dose is gradually decreased as the
condition improves. Adults usually need to stay on a
maintenance dose for life. However, children may be
able to stop steroid treatment after approximately one
year. Some patients cannot tolerate or do not respond
to corticosteroids. These patients may be treated with
immunosuppressive drugs, such as azathioprine or
methotrexate. Other patients may respond well to
intravenous immune globulin. Dermatomyositis often
improves with treatment of malignant tumors.
Self-care
tips
While there
is no known way to prevent dermatomyositis, you can
find relief from symptoms and possible remission by
following your doctor’s treatment recommendations. It
is very important to reduce your physical activity
until your muscles have had the opportunity to
recover.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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