B43-39 The Evolving Role of Transbronchial Cryobiopsy in the Diagnosis and Treatment of Acute Exacerbations of CTD-ILD

Abstract Introduction Connective tissue disease-associated interstitial lung diseases (CTD-ILD) comprise about 25% of ILD cases and represent pulmonary manifestations of systemic autoimmune disorders. Their prevalence and complexity necessitate a strong understanding of diagnosis and treatment. ILD diagnosis relies on high-resolution computed tomography (CT) and pulmonary function testing. For CTD-ILDs, additional rheumatologic evaluation is required. CTD-ILDs are treated with immunosuppressive therapy, while antifibrotics are reserved for progressive fibrosing phenotypes. Other ILDs are managed primarily with antifibrotic agents, avoiding immunosuppression, making early diagnosis essential. Acute ILD flares can mimic other conditions due to nonspecific respiratory symptoms. Transbronchial cryobiopsy (TBCB) has demonstrated utility in directing care, reducing hospital stay, and lowering procedural risks compared to surgical lung biopsy (SLB). We present a case in which TBCB clarified diagnosis and guided management in a complex presentation. Case Presentation A 64-year-old woman with mixed connective tissue disease-related ILD on mycophenolate and 3L home oxygen presented with worsening dyspnea, cough, and chest discomfort. Labs showed leukocytosis with eosinophilia. CT revealed diffuse bilateral bronchiectasis, pulmonary infiltrates, and reticular fibrotic changes. She was initially treated for community-acquired pneumonia; however, oxygen requirements remained elevated. Pulmonology recommended bronchoscopy and TBCB, as SLB was high risk. Steroids were uptitrated, and she was discharged on 5L oxygen. TBCB findings indicated an exacerbation of chronic pulmonary connective tissue disease with a progressive fibrotic phenotype. One month later, CT showed resolution of infiltrates. Steroids were tapered, nintedanib initiated, and oxygen requirements returned to baseline. Figure 1A: CT chest showing diffuse ground-glass opacities with fibrotic changes.Figure 1B: Young fibrosis with subacute inflammation (A) among old fibrosis with type II pneumocyte proliferation and eosinophils (B). Discussion SLB remains the diagnostic gold standard for ILD, yet evidence supports TBCB as a safer alternative. Meta-analyses show higher mortality and morbidity with SLB. Multicenter studies report diagnostic yields of ∼80% with TBCB versus 90% with SLB. Randomized trials using a step-up strategy—starting with TBCB and proceeding to SLB if inconclusive—demonstrated fewer adverse effects (4% vs. 50%) and shorter hospital stays. This case illustrates how TBCB clarified diagnosis and guided therapy in an ILD flare initially misattributed to infection. Despite slightly lower diagnostic yield, TBCB’s reduced risk profile highlights its clinical value. Further research should explore its role across ILD subtypes. This abstract is funded by: None