[Antisynthetase (anti PL-7 antibody) syndrome presenting as a skin rash and exacerbation of interstitial pneumonia during treatment for rheumatoid arthritis].

A 52-year-old man was admitted to our hospital for progressive dyspnea of 3 months duration and a skin rash of 4 months duration. Previously, he had been given a diagnosis of rheumatoid arthritis at age 40, then a diagnosis of interstitial pneumonia at age 46. Tacrolimus and prednisolone were begun at age 50, and 50 mg/week of etanercept was added 17 months before admission to our hospital. Due to renal dysfunction, tacrolimus was discontinued 9 months before admission. A skin rash developed 4 months before admission, and progressive dyspnea developed over the 3 months before admission. Tacrolimus was restarted at 1 mg/day and prednisolone was increased from 5 mg/day to 15 mg/day; however, neither the skin rash nor the dyspnea improved. After visiting a local physician, the patient was then referred to our institution. On presentation, skin changes such as erythema of the superior palpebrae and fingers were noted. His serum creatine phosphokinase level was elevated, but muscle strength was normal and no abnormal electromyographic and muscle biopsy findings were found. Anti-Jo-1 antibody was negative but anti PL-7 antibody was positive. The patient did not meet the diagnostic criteria of dermatomyositis/ polymyositis, so antisynthetase syndrome was diagnosed. Etanercept was discontinued and the prednisolone increased, which resulted in improvement of the interstitial pneumonia and skin rash. Antisynthetase syndrome should be considered as a differential diagnosis when skin rash and exacerbation of interstitial pneumonia are found during treatment for rheumatoid arthritis.