Piecing together the subtle clues of common variable immunodeficiency.

Common variable immunodeficiency (CVID) is a primary immunodeficiency disorder that results in decreased immunity and increased infection risk. This multisystem disorder often presents as recurrent, prolonged respiratory tract infections. Other manifestations include chronic lung disease, systemic granulomatous disease, malignancies, enteropathy, splenomegaly, and autoimmune disease including cytopenias.