Dermatomyositis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Dermatomyositis is a connective-tissue disease that is characterized by inflammation of the muscles and the skin. Its cause is currently unknown, but it may result from either a viral infection or an autoimmune reaction. Up to 50% of the cases may be a paraneoplastic phenomenon, indicating the presence of cancer.
X-ray findings include dystrophic calcifications in the muscles.
There is a form of this disorder that affects children, and it is known as juvenile dermatomyositis.
"Gottron's papules", which are pink patches on the knuckles, and priapisms, are associated with this disorder.
Historical Perspective
Classification
It is classified as juvenile or adult dermatomyositis.
Pathophysiology
The underlying mechanism of dermatomyositis is conjectured to be complement-mediated damage of microscopic vessels with muscle atrophy and lymphocytic inflammation secondary to tissue ischemia. On microscopy, both B- and T-cell infiltrate is seen.
Causes
Possible causes of dermatomyositis could be a viral infection or an autoimmune reaction. It is closely associated with other autoimmune diseases.
Differentiating Dermatomyositis from other Diseases
Dermatomyositis must be differentiated from other common, lymphocyte predominant inflammatory myopathies. Hypothyroidism and sarcoidosis have few common symptoms as dermatomyositis and need to be ruled out.
Epidemiology and Demographics
Risk Factors
Natural History, Complications and Prognosis
Complications related to dermatomyositis are difficulty in swallowing, aspiration pneumonia and skin involvement such as infection and calcinosis. The prognosis of the disease depends upon response to therapy and whether complications appear in the patient.
Diagnosis
History and Symptoms
The main symptoms of dermatomyositis include skin rash and symmetric proximal muscle weakness which may be accompanied by pain. There can also be purple or violet colored upper eyelids. The skin rash is purple-red and over the face, knuckles, neck, shoulders, upper chest, and back.
Physical Examination
Physical examination findings in dermatomyositis include Gottron's sign, a heliotrope rash on the upper eyelids, shawl sign, erythroderma, periungual telangiectasia, cracked skin of hands, psoriaform changes and calcinosis cutis.
Laboratory Findings
Creatine kinase (CK) and aldolase levels may be increased indicating muscle damage in dermatomyositis.
X Ray
X Ray findings include dystrophic calcifications in the muscles and/ or calcium deposits under the skin.
MRI
Other Imaging Findings
Other Diagnostic Studies
A muscle biopsy can in dermatomyositis demonstrates inflammatory cells surrounding and damaging blood vessels in the muscle. Skin biopsy is done to identify dermatomyositis and also to rule out systemic lupus erythematosus.
Treatment
Medical Therapy
There is no cure for dermatomyositis, but the symptoms can be treated. Options include medication, physical therapy, exercise, heat therapy (including microwave and ultrasound), orthotics and assistive devices, and rest. The standard treatment for dermatomyositis is a corticosteroid drug, given either in pill form or intravenously. Surgery may be required to remove calcium deposits that cause nerve pain and recurrent infections.