Common Variable Immunodeficiency Associated With Connective Tissue Diseases: A Report of Two Cases.

Common variable immunodeficiency (CVID) is the most frequent symptomatic primary immunodeficiency in adults and is increasingly recognized as a disorder of immune dysregulation. Autoimmune diseases, including connective tissue diseases, may precede the diagnosis of CVID and contribute significantly to morbidity, particularly through pulmonary involvement. We report two adult women patients with connective tissue diseases (rheumatoid arthritis and primary Sjögren's syndrome) complicated by recurrent respiratory infections, interstitial lung disease, and severe hypogammaglobulinemia. In both cases, the diagnosis of CVID was established after a prolonged diagnostic delay, and immunoglobulin replacement therapy was indicated. These cases highlight the importance of considering CVID in patients with connective tissue diseases who present with recurrent infections or unexplained pulmonary involvement. Early diagnosis and timely initiation of immunoglobulin replacement therapy are essential for improving outcomes and preventing irreversible complications.