Click here to view next page of this article

Dermatomyositis

Dermatomyositis is one of the idiopathic inflammatory myopathies in which characteristic cutaneous disease is present. A related condition known as polymyositis appears to be similar in its muscle pathology, differing only in its lack of skin findings. Recently, another myopathy, known as inclusion body myositis, has been described. Skin findings are rare in this subset of idiopathic inflammatory myopathies. Polymyositis, and less commonly dermatomiositis, may occur in conjunction with other rheumatic diseases such as systemic lupus erythematosus, systemic sclerosis.

The idiopathic inflammatory myopathies are systemic autoimmune disorders that are expressed predominantly in the skin and proximal skeletal musculature. However, other organs such as the lung and heart may be involved. A systemic vasculopathy, which can produce disease in other organs such as the gastrointestinal tract, is frequently present in children with dermatomiositis. In some patients, the florid cutaneous manifestations of dermatomyositis may be present for many years in the absence of clinical and enzymatic evidence of muscle disease (i.e., amyopathic dermatomyositis or dermatomyositis sine myositis).

Dermatomyositis/polymyositis is one of the least common of the

Recommendations

Treatment

Dosage recommendations in this document are for an average-sized, otherwise healthy adult and should be appropriately adjusted when treating children or adults with renal or hepatic dysfunction.

Medical

Topical corticosteroids

Topical corticosteroids usually in an ointment base are occasionally helpful, but care should be taken to avoid producing atrophy. Other forms of topical and systemic anti-pruritic therapy, including oral antihistamines, may be considered when topical corticosteroids are not successful.

Aminoquinoline antimalarials

Oral hydroxychloroquine, 200 to 400 mg/day, can aid in the control of the skin disease in some patients. Partial improvement is more common than complete control. In some patients the addition of quinacrine, 100 to 200 mg/day, can be of benefit, whereas others respond to a switch from hydroxychloroquine to chloroquine, 250 mg/day. Baseline and periodic follow-up ophthalmologic screening for antimalarial retinopathy should be performed for all patients being treated with chloroquine and hydroxychloroquine. Baseline and intermittent tests to evaluate for hematologic and hepatic toxicity with any of these drugs are recommended.

Systemic corticosteroids (oral)

Prednisone, 0.5 to 1.5 mg/kg per day, can be of considerable benefit to some patients with dermatomyositis who do not respond to antimalarials alone. In cases involving disabling skin disease such therapy may be warranted. In some patients treated with systemic corticosteroids, pruritic skin disease activity can persist long after full resolution of muscle weakness. Patients should be monitored carefully while taking systemic corticosteroids. Alternate-day therapy may be considered. Steroid myopathy may be difficult to distinguish from active myositis.

Muscle disease

Systemic corticosteroids

Systemic corticosteroids are used in doses sufficient to control the disease process. In mild cases, alternate-day therapy with as little as 20 mg of prednisone may be sufficient, whereas in severe disease, intravenous methylprednisolone, 1 gm/day, for 3 to 5 days may be necessary. In most cases 0.5 to 1.5 mg/kg of oral prednisone given in one daily dose is sufficient for initial disease control. Once muscle disease activity is controlled, a slow taper of the corticosteroid dose over a 12-month period can minimize the risk of disease recrudescence.

Other immunosuppressive agents

To avoid the long-term side effects of corticosteroids, other corticosteroid-sparing immunosuppressive agents have been used and can lead to disease control and steroid tapering. These agents include, but are not limited to

Oral or intravenous methotrexate

Oral azathioprine

Oral cyclophosphamide or intermittent intravenous pulsed cyclophosphamide

Oral chlorambucil

Oral cyclosporine

Surgical

Surgical removal of medically unresponsive, symptomatic calcium deposits is warranted.

Other Therapy for additionally involved systems

Pulmonary and cardiac disease Corticosteroids and/or immunosuppressive agents

Malignancy Usual therapy for the type of cancer

Evolving

Skin disease

Low-dose methotrexate, azathioprine, and cyclosporine for control of cutaneous inflammatory disease

Diphosphonates, aluminum hydroxide, probenecid, colchicine, and low-dose warfarin to treat the cutaneous calcinosis that can be seen in dermatomyositis (especially in children); however, medical therapy for this difficult condition is often not adequate.

Muscle disease

Intravenous immunoglobulin

Total body irradiation

Plasmapheresis (Recent controlled data have questioned the value of plasmapheresis in ...

More