Antisynthetase syndrome presenting as rheumatoid-like polyarthritis

The antisynthetase syndrome is a systemic inflammatory disease associated with anti-tRNA synthetase antibodies and consisting of the clinical features of inflammatory myopathy arthritis, interstitial lung disease (ILD), fever, Raynaud syndrome, and rash. It rarely presents with symmetric arthritis as the initial manifestation of the disease.

The aim of the study was to describe the clinical, laboratory, and radiographic characteristics of patients with antisynthetase syndrome who presented with symptoms of inflammatory arthritis, mimicking rheumatoid arthritis (RA) at the time of initial evaluation.

Six cases derived from a single university-based rheumatology clinic in Wisconsin are presented. The major clinical, laboratory, radiographic, and histopathologic data are described.

All 6 patients demonstrated symmetric synovitis involving the hands. Five patients met the American College of Rheumatology classification criteria for RA. Three patients had nail-fold capillary abnormalities, and 4 patients were observed to have Raynaud phenomenon. Three patients demonstrated a cytoplasmic pattern when testing for antinuclear antibodies by immunofluorescent assay, and all had t-RNA synthetase antibodies. Two patients had positive rheumatoid factors, but none had strongly positive cyclic citrullinated peptide antibodies. None of the patients demonstrated radiographic erosions. All patients had evidence of ILD by imaging or pulmonary function testing. Prognosis was generally favorable, although disease severity and treatment varied considerably.

In patients who present with features mimicking but atypical for RA, such as early ILD, nail-fold capillary abnormalities, Raynaud phenomenon, cytoplasmic antinuclear antibody pattern, negative cyclic citrullinated peptide antibody status, and nonerosive arthritis, the antisynthetase syndrome should be considered.