LAUSR

TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: Osimertinib induced lung disease may present as a COVID pneumonia. We herein present a case of a 71 year old patient with hypoxic respiratory failure initially treated for COVID pneumonia, to be later diagnosed with Osimertinib induced pneumonitis. CASE PRESENTATION: A 71 year old gentleman with a 20 pack-year smoking history, epidermal growth factor receptor mutated stage IV non-small cell lung cancer with brain metastasis treated with Osimertinib, presented to the emergency room in March 2021 with shortness of breath for three days. On presentation, his oxygen saturation was 87% on room air and increased to 92% with 6 liters per minute (L/min) of oxygen. Contrast Computed Tomography (CT) scan of the chest excluded pulmonary embolism but revealed multifocal patchy opacities along with an interval increase in the size of his primary tumor and pulmonary nodules. Laboratory investigations revealed the absence of leukocytosis with lymphopenia and slightly elevated lactate dehydrogenase and C-reactive protein. COVID pneumonia was suspected despite a negative nasopharyngeal SARS-CoV-2 PCR test. The patient was then started on treatment with Methylprednisolone (20 mg/day twice daily) and Remdesivir (200mg/day followed by 100 mg/day) due to high suspicion for COVID despite the negative test. Given the patient's immunosuppressed state, broad-spectrum antibiotics were also given for a possible bacterial infection. Over the next 24 hours, his oxygen requirements continued to escalate to 15 L/min through high flow nasal cannula. He was then transferred to the intensive care unit for management of hypoxic respiratory failure. Despite treatment for COVID and bacterial pneumonia, the patient's oxygen requirements did not improve. As a result, other differential diagnoses were investigated. Methylprednisolone pulse therapy (1g/day for three days) was started for suspected Osimertinib induced pneumonitis. His oxygenation and symptoms significantly improved over the next 48 hours to 4 L/min. Patient was discharged on Prednisone 60 mg/day and oxygen therapy was discontinued six days after initial presentation. DISCUSSION: We present a case of osimertinib induced pneumonitis. This diagnosis was confirmed based on the rapid clinical improvement following the initiation of high dose steroids. Few case reports in the literature describe this adverse complication and its incidence remains unclear [1]. In our case, pneumonitis developed after approximately five months of Osimertinib treatment in a patient with no previous parenchymal lung disease. Given that this complication could be life-threatening, it should be given urgent attention and the correct treatment should be administered as early as possible [2]. CONCLUSIONS: In conclusion, despite a typical presentation of a hypoxic respiratory failure in the era of the COVID pandemic, other differential diagnosis should always be considered. REFERENCE #1: Matsumoto Y, Kawaguchi T, Yamamoto N, et al. Interstitial Lung Disease Induced by Osimertinib for Epidermal Growth Factor Receptor (EGFR) T790M-positive Non-small Cell Lung Cancer. Intern Med. 2017;56(17):2325-2328. doi:10.2169/internalmedicine.8467-16 REFERENCE #2: Fan M, Mo T, Shen L, Yang L. Osimertinib-induced severe interstitial lung disease: A case report. Thorac Cancer. 2019;10(7):1657-1660. doi:10.1111/1759-7714.13127 DISCLOSURES: No relevant relationships by Eliane Alhalabi, source=Web Response No relevant relationships by Jayna Gardner - Gray, source=Web Response No relevant relationships by Vritti Gupta, source=Web Response