SESSION TITLE: Medical Student/Resident Critical Care Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Herpes simplex virus (HSV) endobronchial lesions are rarely observed. Case reports describe partially or fully obstructing masses in both immunocompetent and immunocompromised patients. Diagnosis requires both visualization and histological evidence in the absence of malignancy. CASE PRESENTATION: A 68 year-old immunocompetent female with a history of oxygen dependent chronic obstructive pulmonary disease presented to the emergency department for dyspnea and cough. Chest x-ray showed atelectasis of the right lung fields with mediastinal shift towards the right and suggested an underlying pleural effusion. Computed tomography of the chest revealed a large right pleural effusion with near complete atelectasis of the right lung and suspicion for a mass in the right lower lobe. The patient required intubation for hypoxemic respiratory failure and was treated for septic shock and pneumonia. A small bore chest tube was placed and subsequent fluid analysis was consistent with empyema. Culture results were treated with appropriate antibiotics. A bedside bronchoscopy was performed for worsening copious secretions and found a partially obstructing endobronchial lesion in the right posterior basal segment. Biopsy and bronchial lavage washings were sent for analysis. While awaiting results the patient was extubated and improving. Bronchoscopy results yielded HSV-1. The patient was started on acyclovir and made a full recovery. DISCUSSION: To our knowledge all reported endobronchial HSV mass lesions have resulted in HSV pneumonia requiring antiviral treatment. Interestingly, our patient improved clinically prior to positive HSV polymerase chain reaction results and was extubated. Most likely the endobronchial lesion led to post-obstructive pneumonia and eventual empyema. What is truly unique is that the herpetic pseudotumor did not appear to result in a viral pneumonia but instead was the nidus for superimposed secondary bacterial infection. We did initiate acyclovir for one week but the severity of our findings were questioned. Studies have looked at HSV’s presence in upper and lower respiratory tract and have found it is not an uncommon finding. As of yet there is not a clear understanding of its pathogenicity. CONCLUSIONS: HSV is a rare cause of endobronchial mass lesions in immunocompetent adults. The clinical significance of this finding is not fully understood at this time and requires further investigation. *HCA Disclaimer “This research was supported (in whole or part) by HCA Healthcare and/or an HCA Healthcare affiliated entity. The views expressed in this presentation represent those of the author and do not necessarily represent the official views of HCA Healthcare or any of its affiliated entities.” Reference #1: Odani, K., Tachibana, M., Tamashima, R., & Tsutsumi, Y. (2019). Herpes Simplex Virus Pneumonia: Importance of Aspiration Etiology. Case Reports in Pathology, 2019, 1-3. doi:10.1155/2019/7623576 Reference #2: Simoons-Smit, A., Kraan, E., Beishuizen, A., Schijndel, R. S., & Vandenbroucke-Grauls, C. (2006). Herpes simplex virus type 1 and respiratory disease in critically-ill patients: Real pathogen or innocent bystander? Clinical Microbiology and Infection, 12(11), 1050-1059. doi:10.1111/j.1469-0691.2006.01475.x Reference #3: Dantas, G. C., Shoji, H., Hoelz, C., Funari, M. B., & Szarf, G. (2017). Herpes simplex lesion mimicking left upper lobe bronchial tumour. Thorax, 73(1), 94-95. doi:10.1136/thoraxjnl-2017-210026 DISCLOSURES: No relevant relationships Added 05/29/2020 by Leonard Hamera, source=Web Response, value=Grant/Research Support Removed 05/29/2020 by Leonard Hamera, source=Web Response No relevant relationships by Jeffrey Jordan, source=Web Response No relevant relationships by Gaurav Shah, source=Web Response