Radiographic Patterns In Patients With Leukemic Infiltration

SESSION TITLE: Imaging Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: Cross-sectional imaging is an essential tool in the evaluation of respiratory illness in patients with hematologic malignancy. Such patients are at high risk for lung infection due to immunocompromise, but they are also vulnerable to various non-infectious pulmonary diseases. These include leukemic infiltration (LI) - an underappreciated and poorly studied complication seen during acute leukemia. Here we sought to better define the radiographic patterns of leukemic infiltrates on chest computed tomography (CT). METHODS: A retrospective analysis was performed on adult patients admitted to Yale New Haven Hospital from 2013-2018 to identify patients with LI. Inclusion criteria were (i) peripheral blast count >3% (indicating active leukemia), (ii) performance of bronchoscopy with bronchoalveolar lavage, and (iii) negative microbiological testing. Of the 38 resulting patients, 34 were deemed to have LI by retrospective chart review performed by three independent reviewers. Key indicators of LI included a correlation between blast count and severity of respiratory illness (e.g. hypoxemia, burden of infiltrates) and nonresponse to therapy for alternative causes (e.g. pulmonary edema, infection). RESULTS: Of the 34 patients with LI, there were 27 with acute myeloid leukemia (9 newly diagnosed and 18 relapsed), 2 with chronic myeloid leukemia, 2 with acute lymphocytic leukemia, 2 with lymphoma and 1 with myelodysplastic syndrome. Bilateral ground glass opacities and bilateral nodules were the most commonly reported CT findings (56% and 41%, respectively). Other findings included pleural effusions (50%) interlobular septal thickening (29%), lymphadenopathy (29%) and bronchial wall thickening (9%). Of note, 28 of 34 CTs in patients with LI were interpreted as likely infection by independent radiologists, and 17 were considered consistent with fungal pneumonia. All 34 cases received broad spectrum antimicrobials with an average duration of 20 ± 4.9 days. Patients underwent an average of 18 ± 2.1 cultures (all negative), 4 ± 1.1 diagnostic imaging tests, and were hospitalized for 22 ± 3 days. CONCLUSIONS: LI has a variable radiographic presentation on chest CT, with bilateral ground glass opacities, nodular changes, and interlobular thickening being the most common features. These non-specific findings are commonly interpreted as infectious, prompting unnecessary microbiological evaluations and antimicrobial therapy. CLINICAL IMPLICATIONS: LI is common in patients with acute leukemia, but often misdiagnosed as infection by chest CT. Recognition that these two conditions are poorly distinguishable by chest CT should aid clinicians in the management of respiratory illness in patients with hematologic malignancy. DISCLOSURES: No relevant relationships by Chace Avery, source=Web Response No relevant relationships by Avi Cohen, source=Web Response No relevant relationships by Charles Dela Cruz, source=Web Response No relevant relationships by Solmaz Ehteshami-Afshar, source=Web Response No relevant relationships by Samir Gautam, source=Web Response No relevant relationships by Peter Kahn, source=Web Response No relevant relationships by Seohyuk Lee, source=Web Response No relevant relationships by Patricia Valda-Toro, source=Web Response