Granulomatous lymphocytic interstitial lung disease in common variable immunodeficiency: an italian multicenter retrospective study

Introduction Common Variable Immunodeficiency (CVID) is the most common symptomatic Primary Antibody Deficiency (PAD) in adults and the most frequently diagnosed symptomatic Inborn Error of Immunity (IEI). Its clinical manifestations can be divided into two categories: infectious and non-infectious, reflecting the dual nature of the disease involving both immune deficiency and immune dysregulation. One of the most severe complications of CVID is Granulomatous Lymphocytic Interstitial Lung Disease (GLILD), a condition associated with poor outcomes and unclear pathogenesis. Objectives This study aimed to analyse GLILD in relation to mortality, pulmonary function, clinical phenotypes, and treatment. A key focus was developing a minimally invasive diagnostic approach by utilizing bronchoalveolar lavage fluid (BALF) analysis, reducing the need for more invasive diagnostic methods such as surgery or excessive radiological exposure. Additionally, we sought to identify clinical and immunological factors linked to a poorer prognosis. Methods We included patients from four Italian Referral Centers for IEI who had either histological or clinical-radiological evidence of GLILD. Patients with more severe manifestations, such as lymphoma, need for immunosuppressive therapy, or death, were categorized as having a poor prognosis (cases). In contrast, the remaining GLILD patients were placed in the good prognosis group (controls). Data for analysis were gathered through a retrospective review of medical records from both cases and controls. Results A total of 64 patients were included in the cohort. The majority were female (72%). Lung and lymph node biopsies frequently showed lymphoid follicular hyperplasia (77% and 95%, respectively) and granulomas (69% and 63%, respectively). Genetic testing was performed on 12 patients, with mutations in TACI (33.3%) and CTLA-4 (25%) detected. All patients had immunoglobulin levels below the normal range at diagnosis (median IgG = 236 mg/dL; IgA = 10 mg/dL; IgM = 18 mg/dL), necessitating replacement therapy for the entire cohort. Extrapulmonary involvement was common (85%), with splenomegaly in 77%, hepatopathy in 31%, immune thrombocytopenia in 50%, and autoimmune hemolytic anemia in 20%. PET-CT scans showed lymph node involvement in the majority of cases (supradiaphragmatic 97%, subdiaphragmatic 85%), along with lung (85%) and spleen (61%) involvement. Cancer was diagnosed in 25% of patients, with half being hematologic malignancies. Regarding lung involvement, pulmonary function tests revealed a reduced DLCO% (median 77% at the first test, 75% at the most recent). CT scans frequently showed lymphadenopathies (79%), nodules (75%), bronchiectasis (54%), and ground-glass opacities (50%). 63% of the cohort received specific treatment (steroids, rituximab, DMARDs), with 67.5% receiving rituximab and 52% responding to therapy. The overall mortality rate was 17%, with infections (46%), lymphomas (18%), and hepatopathy (9%) being the leading causes of GLILD-related deaths. The case-control analysis yielded the following results: cases had a higher prevalence of females (82% vs. 58%; p=0.050), longer diagnostic delays (9 vs. 3 years; p=0.002), and more severe histological findings. Cases also had significantly lower IgG levels at diagnosis (189 vs. 298 mg/dL; p=0.027). In laboratory tests, the CD4+/CD8+ ratio was significantly lower in cases, both in serum (1.10 vs. 1.58; p=0.050) and BALF (1.10 vs. 4.13; p=0.004). Lung function tests showed lower DLCO% in cases (70.5% vs. 91.0%; p=0.002). Radiological findings showed that ground-glass opacities (71% vs. 19%; p<0.001) and bronchiectasis (71% vs. 6%; p=0.004) were more common in cases. We developed a prognostic score based on IgG levels at diagnosis, diagnostic delay since CVID diagnosis, and DLCO% at the first pulmonary function test, achieving a specificity of 95.2%, sensitivity of 75%, and an area under the curve (AUC) of 0.901. Conclusion This study confirmed several established characteristics of GLILD while also providing new insights, including factors that distinguish milder forms from more severe cases. The proposed prognostic score may help predict outcomes in GLILD patients. However, GLILD remains poorly understood, and further prospective studies with larger patient cohorts are necessary to establish more standardized, evidence-based approaches for diagnosing and managing this condition.