Bucillamine-induced Pneumonitis in a Patient with Rheumatoid Arthritis-associated Interstitial Pneumonia: A Case Report and Review of the Literature

An 81-year-old woman with rheumatoid arthritis (RA) who had been treated with bucillamine presented with dyspnea. Computed tomography of the chest showed ground-glass opacities and consolidations in both lungs and honeycombing in both basal lung areas. An elevation of the serum Krebs von den Lungen-6 level and hypoxemia were seen. Lymphocytosis with a decreased CD4/CD8 ratio was seen in the bronchoalveolar lavage fluid. A transbronchial lung biopsy specimen showed organizing pneumonia. Based on a diagnosis of bucillamine-induced pneumonitis (BIP) with RA-associated pre-existing interstitial pneumonia, she was successfully treated with the cessation of bucillamine and systemic corticosteroid therapy. The risk factors and prognosis of BIP are discussed.