SESSION TITLE: Pulmonary Manifestations of Systemic Disease 2 SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 31, 2017 at 01:30 PM - 02:30 PM INTRODUCTION: Pulmonary involvement of chronic lymphocytic leukemia (CLL) is uncommon; typically this is secondary to infection, hemorrhage, or drug toxicity. We present a rare case of an organizing pneumonia secondary to relapse of CLL. CASE PRESENTATION: A 58-year-old man with CLL previously treated with fludarabine, cyclophosphamide, and rituximab presented with several months of progressive cough, fevers, chills, and a ten-pound weight loss. He was treated by his primary care provider with multiple courses of antibiotics without improvement. CT imaging revealed diffuse tree-in-bud opacities and widespread lymphadenopathy. Bronchoscopy was performed and a transbronchial biopsy demonstrated plugs of organizing fibroblastic tissue within airspaces and mild interstitial inflammatory changes consistent with organizing pneumonia. Evaluation for infection, including multiple respiratory cultures, and for underlying connective tissue disease (CTD) was unremarkable. His symptoms and infiltrates resolved with corticosteroid treatment. Around the time of diagnosis, his absolute lymphocyte count was elevated at 9.4 x103 and continued to rise to 38.4 x103 consistent with relapse of his CLL. The patient is currently undergoing further evaluation for potential treatment of CLL. DISCUSSION: Tree-in-bud opacities in the setting of productive cough are most commonly associated with infection, even in patients with CLL. This patient had multiple rounds of appropriate antibiotic therapy with no significant improvement in his symptoms and multiple negative cultures. Connective tissue diseases such as SLE were considered, but serological evaluation was unremarkable and he had no other findings consistent with an active CTD. Though rare, CLL has been implicated as a causative etiology for organizing pneumonia. With an increasing absolute lymphocyte count, it is believed that the most likely etiology for his organizing pneumonia is lung involvement of CLL. CONCLUSIONS: This case describes a rare presentation of organizing pneumonia likely due to pulmonary involvement of relapsed chronic lymphocytic leukemia. Reference #1: Polaczek, M. M., et al, 2015. Organizing pneumonia appearing in B-cell chronic leukemia malignancy progression - a case report. Pneumonol i Alergologia Polska, 83(4):307-11. Reference #2: Moore, W., et al, 2006. Pulmonary Infiltration from Chronic Lymphocytic Leukemia. Journal of Thoracic Imaging, 21 (2), 172-175. Reference #3: Terhalle, E., et al, 2015. ‘Tree-in-Bud’: Thinking beyond Infectious Causes. Respiration, 89, 162-165. DISCLOSURE: The following authors have nothing to disclose: Nicholas Keaton, Nikhil Huprikar, Matthew Peterson, Steven Deas No Product/Research Disclosure Information