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A1731 - Diagnostic Utility of Bronchoalveolar Lavage Among Post-Hematopoetic Stem Cell Transplant Patients with Abnormal HRCT Chest Imaging
Author Block: A. Vose1, A. Jacob2, F. Rafiullah3, T. J. Gross2; 1Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, United States, 2Department of Pulmonary and Critical Care Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, United States, 3Department of Hematology and Oncology, University of Iowa Hospitals and Clinics, Iowa City, IA, United States.
Introduction: High Resolution CT (HRCT) is commonly used to characterize pulmonary complications following hematopoietic stem cell transplant (HSCT). Previous studies examined the utility of CT imaging in evaluating pulmonary infiltrates with neutropenic fever. The association of diagnostic CT findings with bronchoscopy (e.g. BAL) has not been evaluated in the HSCT population. CT imaging is superior to plain films in detecting pulmonary infiltrates in immunocompromised hosts. Most studies in this area were performed prior to modern empiric antimicrobial protocols in HSCT patients. Thus, the contribution of data from BAL to the care of HSCT patients with pulmonary abnormalities detected by CT scan is unclear. A review of HSCT patients from days 0 to 1000 post-transplant was performed to clarify the association of CT and BAL findings in this population. Methods: We performed a retrospective chart review of 140 patients who underwent BAL after HSCT from 2009-2016 for diagnosis of post-HSCT pulmonary complications with CT abnormalities. Patients were then classified based on radiologic findings prior to BAL.Radiologic findings were divided into subgroups and characterized by Fleishner criteria. Subgroups included bilateral findings, unilateral finding, lung nodule, lung nodule with halo sign, cavitary lesion, and tree-in-bud nodularity. Radiologic diagnoses were extracted from radiology reports. Results: 140 total patients were analyzed, 83 (59.3%) were male and 57 (40.7%) were female. Of these, 111 had one bronchoscopy and 29 patients had 2 or more procedures with total analyzed bronchoscopies 181. 175 bronchoscopies were specifically triggered by imaging findings. 135 episodes demonstrated bilateral findings; 32 episodes were unilateral; 25 demonstrated nodular findings, 10 demonstrated nodule with halo sign; 7 demonstrated cavitary lesion; 3 demonstrated tree-in-bud opacities. Of patients with bilateral findings, BAL identified an etiology in 68/135 (50.4%). The most common causes were viral pathogens, many of which were also identified on PCR from nasopharyngeal samples. Of patients with nodular disease +/- halo sign with inferred fungal infection by radiology report, only 4/34 BAL demonstrated fungal isolate or antigen. Conclusions: Our data demonstrate a limited correlation between HRCT findings and BAL confirmed microbiologic diagnosis. Potential reasons for this include the insensitivity of CT in distinguishing noninfectious lung inflammation, organizing pneumonia, pulmonary edema, and active infection. Furthermore, all patients received prophylactic broad spectrum anti-infective regimens potentially reducing ability to detect infection by BAL. With bilateral CT opacities, PCR from nasopharynx should be considered prior to BAL, as viral etiologies were the most common etiology with high BAL concordance.