Dermatomyositis associated with normal serum muscle enzyme levels

Cases of polymyositis or dermatomyositis in which levels of all the serum muscle enzymes are within the normal range throughout the entire clinical course are very rare. It has recently been suggested that when there is no increase in creatine kinase the prognosis in dermatomyositis is poor and there is a higher incidence of malignancy and interstitial lung disease associated with the condition. We describe a rare case of dermatomyositis without increase in serum muscle enzymes, including creatine kinase. No evidence of malignancy or interstitial lung disease was found after a followup of 18 months. In accordance with the report of a similar case, we suggest that the absence of an increase in creatine kinase in dermatomyositis is not necessarily a poor prognostic sign.