Dermatomyositis is an inflammatory condition characterized by muscle weakness and a skin rash. Although the disease primarily affects the muscles and skin, it is a systemic condition and can also involve the lungs, joints, esophagus and sometimes the heart.
In adults, the age of onset is usually between the late 40s and early 60s and in children, symptoms usually begin between 5 and 15 years of age. The condition is more common among females than men.
Some of the symptoms of the condition include:
Skin rash is usually the first symptom to manifest and presents as a dusky red or violet colored rash, sometimes with patchy blue discolorations. This rash is called the helitrope rash. The rash may occur around the eyes and across the face but can also affect other areas such as the knuckles, elbows, knees, chest and back.
These scaly eruptions may be seen on the knuckles, knees and elbows as characteristic features of dermatomyositis, although not every patient develops this symptom.
Telengiectasia refers to the presence of small, dilated blood vessels, also called spider veins. Affected blood vessels may be visible underneath the skin in the tips, sides and nail folds of the fingers.
Psoriasis-like patches may develop across the scalp
Calcium deposits under the skin may also develop, especially in juvenile dermatomyositis.
The progressive muscle weakness seen in dermatomyositis affects the muscles closest to the trunk such as those in the upper arms, shoulders, thighs and hips. The weakness that occurs is symmetrical in nature, affecting muscles on both the left and right sides of the body. Muscle weakness may lead to difficulty climbing stairs, getting up from a sitting position or even raising the arms.
Other general symptoms that may manifest include:
Muscle pain or tenderness
Reviewed by Sally Robertson, BSc