Anti-synthetase syndrome

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Anti-synthetase syndrome (ASS) is a systemic, inflammatory, autoimmune disease that is characterized by inflammatory myositis, polyarthritis associated with interstitial lung disease (ILD) and anti-synthetase autoantibodies.

Pathology

ASS can result from autoantibodies to eight of the aminoacyl-transfer RNA synthetases. These include:

  • anti-JO-1: most common anti-synthetase autoantibody
  • anti PL12
  • anti PL7 - anti-threonyl-tRNA synthetase
  • anti OJ
  • anti EJ
  • anti KS
  • anti ZO
  • anti YRS/tyr

Radiographic features

Imaging findings vary depending on the organ involved.

Chest
CT

The associated interstitial lung disease may usually give either a NSIP pattern, an (OP) organizing pneumonia pattern or a combination (NSIP-OP pattern). A UIP pattern may also occasionally occur . The consolidative regions may decrease or resolve in many cases although the disease can at times progress to fibrosis in more than one third of patients.

Treatment and prognosis

Some medications used include : Corticosteroids, Azathioprine, Mycophenolate mofetil (MMF), calcineurin inhibitors: Tacrolimus and Cyclosporine, Rituximab, Cyclophosphamide and intravenous immunoglobulin (IVIG).