A 20-year-old woman presents to the emergency department complaining of joint pain, myalgias, generalized weakness, and rash.
She has a history of a “condition” diagnosed as a young teenager. She is supposed to take Plaquenil (hydroxychloroquine), but has been noncompliant for months.
She denies fever, cough, headache, dysuria, recent travel, or medication use. The photograph shows her rash.
What is her condition, and what treatment would you provide?
Juvenile dermatomyositis is a rare connective tissue disease resulting from capillary vasculopathy, but it is the most common idiopathic inflammatory myopathy of childhood (85% of cases). (Arthritis Rheum 2003;49:300.)
The condition is more common in girls (1:2-5), and most are diagnosed by age 10. The exact etiology is unknown, but familial predisposition and environmental triggers, including an atypical response to infection, appear to play a role. (Arthritis Rheum 2005;53:166.) Adult onset dermatomyositis peaks in middle age.
The primary presenting symptoms of dermatomyositis are muscle weakness, the characteristic heliotropic rash of the upper eyelids with periorbital edema, malar facial erythema (which does not spare the nasal labial fold like that of systemic lupus erythematosus), poikiloderma of the chest and back (hyper- and hypopigmentation with telangiectasias and skin thinning/atrophy), and Gottron's papules (red scaliness of the bilateral dorsal knuckles).
The weakness is symmetric and proximal (typically deltoid, hip flexors, and neck), which may present as frequent falls or difficulty getting off the floor (positive Gower's maneuver). The clinical course of dermatomyositis can vary in severity from mild weakness to severe muscular dystrophy. Other findings include dystrophic calcinosis (30%), cutaneous ulcerations, lipoatrophy of muscle tissue, abnormal capillaries at the nail fold (tortuous and dilated), dysphonia or dysphagia (from muscle weakness), and myalgias/polyarthritis.
Juvenile polymyositis is similar to juvenile dermatomyositis but does not exhibit the characteristic rash. Rarely, some patients develop cardiac (myocarditis), pulmonary (interstitial lung disease 10%), gastrointestinal (vasculopathy leading to performation), and neurologic disease. (Rheum Dis Clin North Am 2002;28:833.) Some correlation appears to exist with type 2 diabetes (Medicine[Baltimore] 2008;87:70) and malignancies of the cervix, lung, ovaries, pancreas, bladder, and stomach. (Ann Intern Med 1976;84:68.)
No singular validated classification system exists for dermatomyositis. (Rheumatology [Oxford] 2004;43:49; Ann Rheum Dis 2013 Sep 2 [Epub ahead of print]; Curr Opin Rheumatol 2012;24:597.) Most patients with dermatomyositis have some abnormal muscle enzymes including creatine kinase, lactate dehydrogenase, aldolase, aspartate aminotransferase, and alanine aminotransferase. Antibody testing including myositis-specific markers may be helpful but are nonspecific.
Currently no serum tests definitively confirm the diagnosis because the clinical presentation and serological studies vary among individuals. (Medicine [Baltimore] 2006;85:111.) Diagnosing dermatomyositis is typically made by some combination of clinical presentation and findings in muscle, on MRI (Radiographics 2000 Oct; 20 Spec No: S295), and on electromyography. MRI demonstrates areas of inflammatory changes within the muscle. Muscle enzymes and erythrocyte sedimentation rate were not useful markers of disease activity. (Rheumatology [Oxford] 2006;45:1255.)
The differential diagnosis of dermatomyositis includes other causes of rash and muscle weakness but is not limited to psoriasis, myasthenia gravis, other muscular dystrophies, polymyalgia rheumatica, fibromyalgia, other connective tissue diseases, hypothyroidism, electrolyte disturbances, steroid-related myopathy, and infectious myositis.
Optimal treatment of dermatomyositis has not been defined (Rheum Dis Clin North Am 2002;28:833; Mayo Clin Proc 2013;88:83), but glucocorticoids appear to be helpful. Immunomodulators (azathioprine, methotrexate) may also be helpful for initial or refractory therapy. (Am J Med 1993;94:379.)
Poorer prognosis appears to be related to initiation of treatment more than six months after symptom onset, severity of presenting symptoms including limb or respiratory weakness, dysphagia, pulmonary or cardiac involvement, or associated malignancy. (Clin Exp Rheumatol 1996;14:263.)
The patient was restarted on Plaquenil (hydroxychloroquine) in consultation with rheumatology, and scheduled for follow-up in the rheumatology clinic.
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