A40-29 When Infection Is Excluded: Recognizing Granulomatous Lymphocytic Interstitial Lung Disease in Newly Diagnosed Common Variable Immunodeficiency

Abstract Introduction Granulomatous-lymphocytic interstitial lung disease (GLILD) is an uncommon but clinically significant pulmonary manifestation of common variable immunodeficiency (CVID). Because its presentation overlaps with infectious, inflammatory, and granulomatous lung diseases, diagnosis can be challenging, particularly when GLILD represents the initial manifestation of previously unrecognized CVID. Case Presentation A 33-year-old male presented with two weeks of fever, night sweats, and unintentional weight loss after returning from a trip to Mexico City. History was notable for recurrent sinopulmonary infections since childhood. Initial labs revealed mild thrombocytopenia. Computed Tomography (CT) of the chest demonstrated multiple bilateral solid and ground-glass nodular opacities with mediastinal and hilar lymphadenopathy, while CT abdomen showed splenomegaly with abdominopelvic lymphadenopathy. Extensive infectious evaluation, including Human immunodeficiency virus, Tuberculosis, hepatitis B/C, Epstein-Barr virus, Cytomegalovirus and endemic mycoses testing was negative. Immunologic testing revealed hypogammaglobulinemia with reduced gamma globulins on serum protein electrophoresis and a normal kappa/lambda ratio with reduced free lambda chains, supporting a diagnosis of CVID. Radiographic findings were consistent with GLILD. Given his clinical stability and absence of respiratory symptoms, bronchoscopy and lung biopsy were deferred. He received intravenous immunoglobulin replacement therapy and was discharged. Outpatient pulmonology follow up revealed normal pulmonary function tests. He is currently awaiting thoracic surgery evaluation for tissue confirmation. Notably, he had a similar episode approximately ten years earlier, with similar CT findings. Bronchoscopy and surgical lung biopsy at that time revealed acute and organizing lung injury with a reactive perivascular lymphocytic infiltrate but no evidence of infection, vasculitis, granulomatous inflammation, or malignancy, and no unifying diagnosis was established at that time. Discussion This case illustrates GLILD as an initial presentation of CVID and highlights the challenges of diagnosis when biopsy is non-diagnostic or not feasible. His prior biopsy underscores that GLILD can demonstrate variable and nonspecific histopathology; therefore, integration of characteristic imaging findings, exclusion of infectious etiologies, and recognition of immunologic abnormalities is critical for diagnosis. Early identification of CVID-associated lung disease is essential to prevent progressive lung dysfunction. This abstract is funded by: None