Significant Response to Rituximab in Extensive Interstitial Pneumonia With Autoimmune Features

Abstract

Interstitial pneumonia with autoimmune features (IPAF) is a new diagnostic classification initially proposed by the European Respiratory Society/American Thoracic Society Task Force for undifferentiated connective tissue related interstitial lung disease. Currently, choice of therapy is left to the individual provider and consists of corticosteroids and/or immunosuppressants. Rituximab is not a well-established medication to treat IPAF. In this report we present a case of significant response to rituximab in a patient with IPAF who couldn't tolerate prednisone and Azathioprine. CASE PRESENTATION:A 74 year old female with a past medical history of CAD, hypertension, and hyperlipidemia was referred to pulmonary clinic for persistent pulmonary infiltrates on chest X-Ray. She complained of fatigue, dyspnea on exertion, and cough. She denied fever. She was a former smoker with 5 pack-years smoking history. She was treated with PO antibiotics for suspected pneumonia by her PCP without improvement in symptoms. Her vitals were stable, physical exam revealed bilateral inspiratory crackles. CXR prior to clinic showed bibasilar airspace disease. CT Chest displayed multilobar pulmonary opacities with several reverse halo signs. CBC, CMP, and CRP were normal. ESR was mildly elevated. To rule out any connective tissuerelated lung disease, autoimmune work up was sent which showed strong positive ANA (>1:1280) but negative dsDNA, CCP, ANCA panel, SM/RNP, RNP, SM antibody. SSA was positive but not SSb. Rheumatoid factor was positive and Myositis antibody panel was negative except SRP. Fungal panel was negative and PFTs showed only mild reduction in DLCO. Patient had no arthritis, dryness in the mouth, or rash. Based on imaging and positive serologic test, IPAF was diagnosed and immunosuppressive therapy was offered. Patient was started on prednisone and Bactrim. However, due to significant weight gain secondary to prednisone, patient wished to discontinue this therapy. Initially, Mycophenolate Mofetil and later on Azathioprine were started, however, both were stopped due to elevated liver enzymes. Rituximab was prescribed as the primary steroid-sparing agent. Clinically, she responded to treatment well. Repeat CT chest revealed significant improvement of interstitial pneumonia.DISCUSSION: Although evidence-based treatment guidelines for IPAF are yet to be established, there is a significant response to corticosteroids and immunosuppressants such as Azathioprine, Mycophenolate Mofetil and Cyclophosphamide in this cohort of patients. Use of Rituximab for IPAF is not considered a first-line therapy, this case suggests Rituximab can be a viable option as a steroid-sparing agent for those who cannot tolerate other immunosuppressants.CONCLUSIONS: Use of Rituximab for IPAF is not considered a first-line therapy, this case suggests Rituximab can be a viable option as a steroid-sparing agent for those who cannot tolerate other immunosuppressants.