23. Non-specific interstitial pneumonia and polymyositis as a manifestation of antisynthetase syndrome with anti-EJ antibodies

Abstract

We present a case of a 48-year-old woman who developed synchronous proximal myopathy and colorectal adenocarcinoma. Muscle biopsy demonstrated an inflammatory necrotizing myopathy, and routine autoimmune screens and paraneoplastic screens were negative. Testing was undertaken for antisynthetase antibodies, demonstrating positivity for anti-EJ antibodies. The patient developed progressive shortness of breath, and shortly thereafter succumbed to bronchopneumonia. Findings at autopsy confirmed the presence of interstitial lung disease, with a non-specific interstitial pneumonia pattern. Antisynthetase syndrome is a systemic autoimmune disease associated with autoantibodies to certain aminoacyl-tRNA synthetases, and is characterized typically by myositis, polyarthritis and interstitial lung disease. Aminoacyl-transfer RNA synthetases are a family of cytoplasmic enzymes that catalyze amino acid attachment to corresponding aminoacyl-tRNAs during the translation phase of protein synthesis. In this case, the autoantibody is to the glycyl-transfer RNA synthetase, one of the rarest described antisynthetase autoantibodies. We present a case of a 48-year-old woman who developed synchronous proximal myopathy and colorectal adenocarcinoma. Muscle biopsy demonstrated an inflammatory necrotizing myopathy, and routine autoimmune screens and paraneoplastic screens were negative. Testing was undertaken for antisynthetase antibodies, demonstrating positivity for anti-EJ antibodies. The patient developed progressive shortness of breath, and shortly thereafter succumbed to bronchopneumonia. Findings at autopsy confirmed the presence of interstitial lung disease, with a non-specific interstitial pneumonia pattern. Antisynthetase syndrome is a systemic autoimmune disease associated with autoantibodies to certain aminoacyl-tRNA synthetases, and is characterized typically by myositis, polyarthritis and interstitial lung disease. Aminoacyl-transfer RNA synthetases are a family of cytoplasmic enzymes that catalyze amino acid attachment to corresponding aminoacyl-tRNAs during the translation phase of protein synthesis. In this case, the autoantibody is to the glycyl-transfer RNA synthetase, one of the rarest described antisynthetase autoantibodies.