| The following vignette applies to the next 2 items. |
A 55-year-old woman comes to the physician due to a 2-month history of malaise, mild fever, and difficulty climbing stairs and rising from a chair. She has unintentionally lost 9.1 kg (20.1 lb) over this period. The patient has hypertension and asthma. Medications include amlodipine, as-needed albuterol, and inhaled glucocorticoids during winter. The patient does not smoke or use illicit drugs. She worked for 20 years supervising cotton processing in a textile factory but has been working as a secretary for the past 10 years. Temperature is 37.8 C (100 F), blood pressure is 120/70 mm Hg, pulse is 82/min, and respirations are 12/min. Chest examination reveals clear lung fields and normal S1 and S2. The patient has bilateral proximal upper and lower extremity weakness with normal reflexes. Plantar reflexes are down-going bilaterally. Violaceous papules and plaques are seen on the dorsum of both hands, as shown in the image below:
Show Explanatory Sources
Kidney and liver function are within normal limits. Creatine kinase level is 1,200 IU/L.
Item 1 of 2
Which of the following is the best next step in management of this patient?
Clinical features of dermatomyositis | |
Muscle weakness |
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Skin findings |
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Extramuscular findings |
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Diagnosis |
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Management |
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CPK = creatine phosphokinase; EMG = electromyography; LDH = lactate dehydrogenase; LE = lower extremity; UE = upper extremity. | |
This patient has proximal myopathy (as evidenced by difficulty rising from a chair and climbing stairs) as well as an elevated creatine kinase level. An insidious onset of symmetric proximal myopathy associated with Gottron papules (ie, violaceous papules/plaques on the dorsal hands, as seen in this patient) or a heliotrope rash is highly characteristic of dermatomyositis.
The diagnosis of dermatomyositis is based primarily on clinical findings and serologic tests.
Because dermatomyositis is associated with interstitial lung disease (ILD), chest x-ray is performed to screen for ILD if no pulmonary symptoms are present; in patients with respiratory symptoms and those with abnormal x-ray findings, CT scan of the chest and pulmonary function testing are recommended.
(Choices A and C) Patients with nonspecific findings (eg, facial erythema, psoriasiform scalp lesions), isolated skin/muscle involvement, or negative antibody testing may need tissue (eg, muscle, skin) biopsy for diagnosis. However, biopsy is not needed for those with characteristic clinical findings and serologic confirmation.
(Choice D) Glucocorticoids can cause proximal myopathy but not the characteristic skin findings of dermatomyositis. Myopathy is unusual with an oral prednisone dose <10 mg or inhaled glucocorticoids.
(Choice E) In HIV myopathy, proximal muscle weakness is more prominent in the lower extremities and is accompanied by myalgias and muscle tenderness. In addition, the violaceous lesions of HIV-associated psoriasis have more scaling and more extensive involvement (nails, palms, and soles) than Gottron papules.
Educational objective:
Dermatomyositis presents with symmetric proximal muscle weakness, elevated creatine kinase, and skin lesions (eg, Gottron papules, heliotrope rash). Diagnosis is based primarily on clinical features and serum antibody testing. Antinuclear antibody test is sensitive, and confirmatory tests include myositis-specific antibodies (eg, anti-Jo, anti-Mi2). Muscle and skin biopsies are needed only if the diagnosis is uncertain.