Acute exacerbation of interstitial pneumonia associated with rheumatoid arthritis during the course of treatment for Pneumocystis jirovecii pneumonia: a case report

BACKGROUND: Pneumocystis jirovecii pneumonia (PCP) is potentially fatal infectious complication in patients with rheumatoid arthritis (RA) during immunosuppressive therapy. Hospital survival due to human immunodeficiency virus—unrelated PCP reaches to 60 %. The high mortality rate results from difficulties in establishing an early diagnosis, concurrent use of prophylactic drugs, possible bacterial coinfection. We herein report a case of PCP in RA patients who developed the architectural distortions of lung in spite of combined modality therapy. CASE PRESENTATION: A 73-year-old Japanese woman with RA was admitted with shortness of breath. Five weeks previously, she had been started on etanercept in addition to methotrexate (MTX). Chest computed tomography (CT) demonstrated diffuse ground glass opacities distributed throughout the bilateral middle to lower lung fields, and serum β-d-glucan was elevated. Bronchoalveolar lavage fluid revealed no P. jirovecii, but the organism was detected by polymerase chain reaction method. Trimethoprim/sulfamethoxazole was administered with methylprednisolone pulse therapy. However, the follow-up chest X-ray and chest CT demonstrated aggravation of the pneumonia with architectural distortions. Additional direct hemoperfusion with polymyxin B-immobilized fibers and intravenous cyclophosphamide therapy were insufficiently effective, and the patient died on day 25. CONCLUSION: The architectural distortions of lung should be considered as a cause of death of PCP. For this reason, a high suspicion of this infectious complication must be kept in mind in order to establish an early diagnosis and treatment in patients with RA managed with MTX and biologics.