[A case of interstitial pneumonia with anti-signal recognition particle (SRP) antibody without myopathy]

Interstitial pneumonia in a 54-year-old woman was diagnosed in April 2007, without symptoms. She was admitted to our hospital in February 2009 because chest radiography showed gradual worsening. On physical examination, she had fine crackles on chest auscultation and "mechanic's hands", without arthritis, myopathy, or Reynaud disease. On laboratory tests, antinuclear antibody (speckled and cytoplasmic pattern) and anti SS-A antibody were positive. Chest CT showed ground-glass opacities in both lower lobes with volume loss and she had a restrictive disorder on a pulmonary function test. Bronchoalveolar lavage was within almost normal limits. For a definitive diagnosis, video associated thracoscopic surgery was performed. The histopathological findings showed a fibrotic nonspecific interstitial (f-NSIP) pattern. Corticosteroid therapy (prednisolone, initially 40 mg/day) was started, and the chest radiography improved. Later, an RNA immunoprecipitation test was positive for anti-signal recognition particle (SRP) antibody. This is a rare case of interstitial pneumonia with anti-SRP antibody without myopathy.