C42-34 Pulmonary Nodulosis in a Rheumatoid Arthritis Patient, a Rare Side Effect of Leflunomide

Abstract Introduction Rheumatoid arthritis (RA) can affect many organ systems. When the lung is involved, lung presentations are also variable. One of these entities is rheumatoid nodules. They occur in 1-20% of patients with rheumatoid arthritis. Pulmonary rheumatoid nodules can be single or multiple, and in varying sizes ranging from millimeters to centimeters. Cavitation of rheumatoid nodules is a much rarer entity. We present a case of a patient with known multifocal rheumatoid nodules in the lung with slow increase in size of these nodules and subsequent cavitation. We attributed the changes in the nodules to the medication leflunomide used to treat the RA in this patient. Case Report 63-year-old Caucasian male non-smoker with a past medical history of seropositive rheumatoid arthritis diagnosed at age twenty-one. The patient was found to have rheumatoid nodules on imaging since 2016. He had been on multiple RA medications over the years. For the past 3 years, his regimen included low dose prednisone, leflunomide and tocilizumab. Cross sectional imaging of the chest during this time began to show increasing size of the previously stable pulmonary nodules with subsequent cavitation. This significant enlargement and cavitation seemed atypical for RA nodules and a thorough review of his medications was done. To rule out infection and malignancy, robotic bronchoscopy was performed and showed no evidence of infection or malignancy. Cryobiopsy demonstrated focal granulomatous inflammation with necrosis. On the suspicion that leflunomide could be contributing to the increasing nodule size and cavitation, the medication was stopped. Follow up CT chest after discontinuing the leflunomide showed decrease in the size of the nodules. Discussion Pulmonary nodulosis is an entity where there is rapid development or increase in the size of existing rheumatoid nodules. It has been reported in a few case reports to temporally related to the drugs used to treat RA such as leflunomide, azathioprine, methotrexate. TNF-alpha antagonists. The mechanism of why these medications can promote RA nodule development and growth is not clear. Our case represents an interesting and important example of pulmonary nodulosis almost certainly due to leflunomide. Malignancy and infection were ruled out and the nodules decreased in size after this medication was held. It is important that pulmonologists and rheumatologists be aware that in patients with RA nodules in the lung that are enlarging and/or cavitating, the medications used to treat RA may be the culprit. This abstract is funded by: None