METHOTREXATE MASQUERADING AS PNEUMONIA: A CASE OF METHOTREXATE-INDUCED LUNG INJURY

SESSION TITLE: Wednesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: Methotrexate is an antimetabolite that has been used to treat acute lymphoblastic leukemia, osteosarcoma and lymphoma, rheumatoid and psoriatic arthritis, and ectopic pregnancies. It has been involved in adverse pulmonary reactions, such as pneumonitis, pulmonary edema, pulmonary fibrosis, and pleuritis. This case of methotrexate induced lung injury in a patient with RA presented as pneumonia. CASE PRESENTATION: 72-year-old female smoker with RA and OSA presented with cough and shortness of breath of 1 month duration. She was empirically treated for CAP with ceftriaxone and azithromycin and was continued on her home dose of MTX and prednisone. The leukocyte count was 10,800 cells/mm3. Imaging findings from the chest x-ray and CT scan showed pulmonary fibrosis in a usual interstitial pneumonia pattern. Procalcitonin, cultures, and serology were negative and consequently ceftriaxone and azithromycin were discontinued. Bronchoalveolar lavage (BAL) showed elevation in neutrophils (14%) and macrophages (77%). Biopsies showed changes consistent with subacute or chronic methotrexate induced lung injury. MTX was discontinued and the patient was sent home on a steroid tapering dose. DISCUSSION: Both high and low doses of MTX has been shown to cause lung injury. MTX lung injury onset can range from 32 weeks after initially starting treatment to after 30 years of MTX use. Identifying the dose and duration of MTX use with the onset of lung injury can help clinicians anticipate potential onset of MTX lung injury. The exact mechanism by which methotrexate induces lung injury is unclear and warrants further investigation via characterization of the BAL features. There have been varying histopathological results associated with MTX lung injury, some of which have been described as desquamative with eosinophilia, immature fibrosis, and pneumocyte-reactive and -proliferative changes. However, cases of mixed or minimal changes on histopathology can be difficult to interpret and there is no single feature that confirms diagnosis. Associated risk factors such as male gender, smoking history, and preexisting lung disease can predispose individuals who are on MTX to MTX lung injury. CONCLUSIONS: Our patient who presented clinically with pneumonia was ultimately diagnosed with MTX lung injury. BAL showed elevations in neutrophils and macrophages and biopsies showed patchy chronic inflammation, reactive epithelial changes, and septal fibroplasia. Although the BAL and the biopsy were atypical of MTX lung injury, the findings were reported as subacute or chronic MTX induced lung injury. With our case, we intend on conducting a literature review to further characterize if there is a dose and duration dependent association with MTX lung injury. We also look to examine the various lung pathology and BAL findings induced by or associated with MTX use and the risk factors that may contribute to MTX lung injury. Reference #1: Wojtuszkiewicz A, Peters GJ, van Woerden NL, et al. Methotrexate resistance in relation to treatment outcome in childhood acute lymphoblastic leukemia. J Hematol Oncol. 2015;8:61. Published 2015 May 29. https://doi.org/10.1186/s13045-015-0158-9 Reference #2: Howard SC, McCormick J, Pui CH, Buddington RK, Harvey RD. Preventing and Managing Toxicities of High-Dose Methotrexate. Oncologist. 2016;21(12):1471-1482. Reference #3: Lipscomb G. Medical Therapy for Ectopic Pregnancy. Seminars in Reproductive Medicine. 2007;25(2):093-098. https://doi.org/10.1055/s-2007-970048. DISCLOSURES: No relevant relationships by Lawrence Goldstein, source=Web Response No relevant relationships by Nishok Karthikeyan, source=Web Response No relevant relationships by Anique Mustafa, source=Web Response No relevant relationships by Terrence Park, source=Web Response No relevant relationships by Rubin Pradhan, source=Web Response No relevant relationships by geeti sharma, source=Web Response No relevant relationships by Vishnu charan Suresh kumar, source=Web Response