A case of interstitial pneumonia associated with anti-PL-7 antibody in a patient with rheumatoid arthritis

A 65-year-old female had been treated rheumatoid arthritis (RA), interstitial pneumonia (IP) and nephrotic syndrome with prednisolone and cyclosporine. She was emergently admitted to our hospital due to the worsening exertional dyspnea and severe hypoxemia. Chest computed tomography (CT) showed new diffuse ground-glass opacities (GGOs) with slight consolidations along with bronchovascular bundle were observed in addition to pre-existing reticular shadows in both lungs with lower lobe-predominance. An acute exacerbation (AE) of pre-existing IP triggered by an infection was suspected, and the treatment with antibiotics and corticosteroid pulse therapy improved her general condition and chest radiological findings. Because some auto-antibodies associated with acute/subacute onset IP have recently become available in clinic, we examined those including anti-aminoacyl tRNA synthetase (ARS) antibodies, and found that she was positive for anti-PL-7 antibody. We diagnosed her anti-synthetase syndrome (ASS) without symptom of myositis, and her IP was considered to be ASS-related. The careful consideration is necessary to precisely diagnose and treat the patients with RA-associated interstitial lung diseases as the several etiologies may be overlapped in the same patient.