TOPIC: Lung Cancer TYPE: Medical Student/Resident Case Reports INTRODUCTION: Non-resolving pneumonia is defined as pneumonia with slow or incomplete resolution despite adequate appropriate antibiotic treatment. It is a common reason for pulmonary consultations & bronchoscopies in the hospital. Though occurrence is relatively rare, there are many reasons non-resolving pneumonia may develop. Often, they are caused by resistant organisms, mechanical airway obstructions, inappropriate antibiotic treatment, & inadequate duration of treatment. We present a rare case of non-resolving pneumonia, which led to irreversible respiratory failure. CASE PRESENTATION: A 68-year-old male with no significant past medical history presented with worsening dyspnea on exertion & cough productive of yellowish sputum for 5 weeks. In the ER, he reported fevers, night sweats, & unintentional 10-lb weight loss. Vitals showed tachycardia & hypoxia. Physical exam was positive for decreased breath sounds on the right with rhonchi. The patient had not seen a physician for many years. He reported smoking 1 pack per day for 50 years. Chest X-ray showed extensive opacification of the right hemithorax with a small pleural effusion, which suggested multi-lobar right lung pneumonia. The patient was started on empiric piperacillin-tazobactam & vancomycin. Sputum culture grew normal respiratory flora. Blood cultures remained negative. Extensive infectious workup was performed with all tests being negative. CTPA revealed airspace opacities within the right lung & fluid density within the right lung apex which is consistent with early lung necrosis. Bronchoscopy showed a normal bronchial tree. Bronchoalveolar lavage cytology showed no malignant cells. After 10 days of no clinical improvement, a repeat CT chest showed worsening right lung opacification, ground-glass opacities within the left upper lobe, & enlarged mediastinal lymph nodes. The patient continued to worsen clinically therefore underwent right limited thoracotomy & lung biopsy, which showed extensive adhesions with pleural & lung implants. Pathology revealed lung adenocarcinoma. The patient declined therapeutic chemotherapy treatment & opted to go home with hospice. DISCUSSION: This case emphasizes the importance of early recognition of non-resolving pneumonia, the proper diagnostic approach, & when to initiate further invasive workup. Evaluation of a patient with a slowly or incompletely resolved pneumonia starts with a careful history, physical examination, & review of the medical record CONCLUSIONS: Consideration of risk factors for delayed resolution should include age, comorbidities, the severity of pneumonia, & specific pathogens. If indicated, further evaluation should include CT chest to assess for findings suggestive of an alternative diagnosis. When pneumonia fails to resolve, bronchoscopy should be considered. Patients with a negative bronchoscopy examination should undergo further evaluation with lung biopsy to assess for malignancy REFERENCE #1: Jameson, J. L., Kasper, D. L., Longo, D. L., Fauci, A. S., Hauser, S. L., & Loscalzo, J. (2018). Harrison's principles of internal medicine. New York: McGraw-Hill Education. DISCLOSURES: No relevant relationships by Luqman Baloch, source=Web Response No relevant relationships by Luqman Baloch, source=Web Response No relevant relationships by Adrienne DaGue, source=Web Response No relevant relationships by ayobami olaleye, source=Web Response