Pulmonary Complications in Acute Myelogenous Leukemia in the Post-Allogeneic Hematopoietic Stem Cell Transplant Period: Diagnostic Yield of Bronchoalveolar Lavage and Biopsy: A Single-Center Experience.

BACKGROUND: Pulmonary complications occur in 40-60% of hematopoietic stem cell transplant (HSCT) patients and carry high mortality. Due to variable diagnostic yield and procedure-related complications, the role of bronchoalveolar lavage (BAL) and transbronchial biopsy remains unclear. We evaluated the infectious and non-infectious diagnostic yield of BAL in acute myelogenous leukemia (AML) patients post-HSCT. METHODS: We performed a retrospective cohort study of adult patients with AML who underwent allogeneic HSCT at a tertiary academic center from 2012 to 2023 and subsequently underwent bronchoscopy with BAL for pulmonary complications within 3 years post-transplant. RESULTS: Of 435 patients, 66 (62% male; median age 58 years) underwent BAL at a median of 191 days post-HSCT. Most procedures were performed in critically ill patients: 59% were in the ICU, 47% were intubated, and 41% had septic shock. Prior to bronchoscopy, 81% received empiric antibacterial therapy (median 8.5 days) and 54% received antifungal therapy. The overall diagnostic yield was 32% and microbiologic yield was 20%. BAL identified clinically significant pathogens including Mucorales species, Aspergillus species, cytomegalovirus, and Mycobacterium tuberculosis. BAL galactomannan was the sole criterion for probable aspergillosis in 3 cases. Bronchoscopy led to antimicrobial management changes in 33% of patients. Pneumothorax occurred in 3%; no procedure-related mortality was observed. CONCLUSION: BAL demonstrated a 32% diagnostic yield and 20% microbiologic yield in AML patients with post-HSCT pulmonary complications, identifying opportunistic infections not detectable by noninvasive testing. Despite prior antimicrobial exposure, BAL influenced management in one-third of cases, supporting its role as a targeted diagnostic and stewardship tool.