Rare radiographic presentation and etiology of organizing pneumonia

SESSION TITLE: Signs and Symptoms of Chest Disease SESSION TYPE: Rapid Fire Case Reports PRESENTED ON: 10/09/2023 09:40 am - 10:25 am INTRODUCTION: Organizing pneumonia (OP) falls under the umbrella of diffuse parenchymal lung disease and can be seen with malignancy, infection and drug-induced lung injury. When an underlying etiology cannot be ascertained, it is termed 'cryptogenic organizing pneumonia' (COP). OP can present with variable radiographic findings but most commonly presents with patchy airspace consolidations or ground glass opacities (GGO). We present a case of OP with unusual radiographic findings with an uncommon infectious etiology. CASE PRESENTATION: A 67-year-old male presented with low grade fevers, dry cough, and shortness of breath at rest for two weeks. His medical history was significant for pulmonary embolism, atrial fibrillation, and coronary artery disease. Initial vital signs were T 101.3 F, HR 110, RR 26, BP 116/92, saturating 97% on BIPAP. Physical examination findings were significant for mild respiratory distress, coarse breath sounds and fine crackles in the bilateral lower lobes. Laboratory workup revealed a white blood cell count of 26/µL with left shift and lactic acid of 3.7mg/dL. Chest x-ray revealed peripherally distributed interstitial opacities. Initial management included broad spectrum antibiotics. A sputum culture grew Pseudomonas aeruginosa which was covered by this regimen. The patient's condition improved initially but after several days, he continued to remain symptomatic and hypoxemic. CT chest revealed diffuse tree-in-bud nodularity and extensive GGO. Viral panel and auto-immune workup were negative. Bronchoscopy with bronchoalveolar lavage (BAL) and transbronchial biopsies (TBBX) were performed. BAL fluid was negative for infection. Histopathology of TBBX showed fibroblastic plugs, organization in the alveolar space, mild interstitial inflammation with lymphocytes and plasma cells, and preserved lung architecture consistent with OP. He was started on corticosteroids with immediate improvement in symptoms and radiologic abnormalities. DISCUSSION: Radiologic abnormalities in OP most commonly demonstrate patchy diffuse consolidations involving the bilateral lower zones. A "tree-in-bud" pattern is a less common finding on imaging of patients with OP. It typically correlates with small airway and respiratory bronchiole predominant disease causing severe airflow limitation. Also, COP presenting with a micronodular pattern tends to have a more rapid progression. Furthermore, to our knowledge, there has been only one case report in the literature of OP caused by infection with Pseudomonas aeruginosa. CONCLUSIONS: Our patient developed OP in response to infection with Pseudomonas aeruginosa, an unusual inciting pathogen. Additionally, his radiological abnormalities were atypical of OP. It is important for clinicians to be aware of the variable radiographic findings for OP as early recognition, prompt diagnosis and treatment are essential to reduce the morbidity and mortality. REFERENCE #1: Chandra, Deepak, Ruby Maini, and Daniel M. Hershberger. "Cryptogenic organizing pneumonia." StatPearls [Internet]. StatPearls Publishing, 2021. REFERENCE #2: Bots, E. M. T., et al. ""Tree in bud" attributable to organizing pneumonia." Thorax 68.4 (2013): 399-400. REFERENCE #3: Lebargy, François, et al. "Micronodular pattern of organizing pneumonia: Case report and systematic literature review." Medicine 96.3 (2017). DISCLOSURES: No relevant relationships by Joseph Bahgat No relevant relationships by Daniel Condit I own stock in Pfizer relationship with Pfizer pharmaceuticals Please note: Many years Added 03/31/2023 by Jennifer Kanaan, source=Web Response, value=Stock dividends No relevant relationships by Ameer Rasheed No relevant relationships by Sruti Velamakanni