SESSION TITLE: Case Report Semifinalists 11 SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/21/2019 02:30 PM - 03:15 PM INTRODUCTION: All too frequently, chest imaging provides a broad and non-specific differential, with inability to differentiate between infectious, fibrotic, inflammatory or malignant changes. Each of these etiologies has an entirely different prognosis and treatment, making it essential to ensure proper diagnosis. The standard for differentiating between these etiologies, and more specifically the diagnosis of cancer, is a surgical lung biopsy. However, the advent of transbronchial cryobiopsy (TBCB) has provided a less invasive means of obtaining adequate tissue to maintain the specificity and sensitivity to make an accurate diagnosis; which in the diagnosis of malignancy is of the upmost importance. We describe five cases in which thoracic imaging on patients admitted for acute hypoxic respiratory failure was interpreted as diffuse parenchymal lung diseases, and were ultimately found to be disseminated malignancies via transbronchial cryobiopsies: CASE PRESENTATION: Case 1: 55 year-old man with known history of cutaneous T cell lymphoma (mycosis fungoides type) with bilateral peribronchovascular consolidation and ground glass opacities believed to be non-specific interstitial pneumonia vs organizing pneumonia. Blind TBCB from RB8, RB9, RB10 while on mechanical ventilation in the ICU found mature T cell lymphoma. Case 2: 65 year-old woman with CT chest showing nodular septal thickening with consolidation believed to by organizing pneumonia underwent TBCB of RB2 RB4, and RB9 showing TTF-1 positive acinar predominate adenocarcinoma with micropapilla. Case 3: 65 year-old woman with a history of stage IIIc squamous cell carcinoma of the right upper lobe had a CT showing a new left lower lobe ground glass infiltrate believed to be organizing pneumonia. TBCB of LB10 demonstrated an adenocarcinoma with papillary features. Case 4: 68 year-old man with a history of stage IIb adenocarcinoma of the right upper lobe status post lobectomy who presented with a worsening ground glass opacification with central cavitation. Three TBCB were obtained from the right lower lobe demonstrating cystic adenocarcinoma. Case 5: 72 year-old woman with recently diagnosed stage IV pancreatic cancer was found with diffuse multilobar pulmonary nodules of varying size. TBCB of RB3, RB8, and RB9 found tissue consistent with metastatic pancreatic cancer. DISCUSSION: While the utility of cryobiopsy is still unfolding, this case series highlights the use of TBCB as a means for providing an accurate diagnosis of malignancy. While these patients demonstrated diffuse radiographic changes rather than single pulmonary lesions, TBCB provided a significant tissue that was successfully stained and sent for molecular analysis in each of these cases. CONCLUSIONS: As new oncologic treatments revolutionize modern medicine, with a push towards immunotherapy, the ability to obtain adequate and intact tissue samples is of the upmost importance. Reference #1: Liang, W., Zhao, Y., Huang, W., Liang, H., Zeng, H., and He, J. (2018). Liquid biopsy for early stage lung cancer. Journal of thoracic disease, 10(Suppl 7), S876-S881. Reference #2: Babiak, A., Hetzel, J., Krishna G., Fritz, P., Moeller, P., Balli, T., and Hetzel, M. (2009). Transbronchial Cryobiopsy: A New Tool for Lung Biopsies. Respiration. 78( 2), 203–208., https://doi.org/10.1159/000203987. Reference #3: Utz JP., Ryu, JH., Douglas, WW., Hartman, TE., Tazelaar, HD., Myers, JL., Allen, MS., and Schroeder, DR. (2001). High short term mortality following lung biopsy for usual interstitial pneumonia. European Respiratory Journal, 17 (2). 175-179. DISCLOSURES: No relevant relationships by Sadia Benzaquen, source=Web Response no disclosure on file for Arjan Flora; No relevant relationships by Rhea Rubin, source=Web Response