Antisynthetase syndrome complicating the course of established case with rheumatoid arthritis: A rare and under-recognized overlapping disease.

A 52-year-old male patient developed RA in March 2009 at the age of 43, with symmetric polyarthritis and active synovitis affecting hands, knees, ankles and both feet without symptoms or signs suggestive of extra-articular features. Laboratory investigations showed negative RF and positive anti-CCP antibodies, negative ANA, negative anti-dsDNA antibodies; the X-rays of both hands showed typical erosive changes in RA and fulfilled the new ACR/EULAR (2010) criteria of RA. The patient achieved remission on a combination of DMARDs. He did well until January 2017 when he developed acute onset of progressive chest pain, dyspnea, and acute respiratory failure. High-resolution CT of the lung showed extensive areas of ground glass veiling, and interstitial subpleural infiltrates were found consistent with aggressive interstitial lung disease (ILD). Autoantibodies against extractable nuclear antigens were screened and showed positive results for anti-RO and anti-Jo1 autoantibodies. The positive anti-Jo1was an expression of anti-synthetase syndrome complicating the RA course and explained the rapidly aggressive course of ILD.