EUH Resident Report: What is antisynthetase syndrome?

The Bottom Line: Antisynthetase syndrome is a clinical condition characterized by arthritis, mechanic’s hand sign, interstitial lung disease (ILD), fever, Raynaud’s phenomenon, and myositis. ILD is the most severe manifestation, occurring in approximately 80% of antisynthetase syndrome patients, and is associated with high morbidity and mortality. Current treatment is based on corticosteroids and a wide number of immunosuppressive drugs, although no clinical trials on this condition have been reported. Prognostic factors in ILD related to antisynthetase syndrome have not been entirely defined.

Summary: A 2012 NEJM case report provides the following clues for diagnosis: The eyelid edema and erythema with pruritus are very characteristic of the heliotrope rash that is associated with dermatomyositis. Malar erythema also occurs and differs from the typical “butterfly rash” of SLE. In SLE, the nasolabial folds are spared from rash, whereas in dermatomyositis, they are not. Other salient features of the antisynthetase syndrome include interstitial lung disease, arthritis, fever, markedly elevated levels of muscle enzymes (creatine kinase, aldolase, and the aminotransferases, with the aspartate aminotransferase level higher than the alanine aminotransferase level), and perhaps most important, a negative ANA test but a positive test for anticytoplasmic autoantibodies.

For treatment, immunosuppressive agents, typically glucocorticoids, with methotrexate or azathioprine as the most common additional agents, are typically used and may result in clinical improvement in patients with inflammatory myositis. Intravenous gamma globulin has been shown to be effective in a controlled study of dermatomyositis.

The patient in the case report continued to have progressive pulmonary disease, fever, myositis, and arthritis and required variable doses of ibuprofen, prednisone, and methotrexate to control the symptoms. The typical rash of the antisynthetase syndrome — mechanic’s hands — eventually developed, and therefore, the patient had all the features of this syndrome.

References: Christopher-Stine , L., et al. (2012). “Case 37-2012.” New England Journal of Medicine 367(22): 2134-2146.

Rojas-Serrano, J., et al. (2015). “Prognostic factors in a cohort of antisynthetase syndrome (ASS): serologic profile is associated with mortality in patients with interstitial lung disease (ILD).” Clinical Rheumatology 34:1563-1569.

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