The Immunocompromised Patient: Non-AIDS

Abstract

Immunosuppression may be primary (i.e. congenital) or secondary (i.e acquired). Because immunodeficiencies constitute an extensive and highly heterogenous group of diseases, imaging interpretation must be performed in light of the underlying condition and/or treatment timeline whenever possible. Secondary immunodeficiencies include those occurring in bone marrow transplant (BMT) and solid organ transplant recipients and in patients on chronic corticosteroid therapy. Familiarity with the time course of immune dysfunction following BMT is essential for providing a narrow differential diagnosis in cases of opportunistic infection. Opportunistic infections in BMT recipients can be categorized based on the post-transplant phase: Neutropenic phase (<30 days, before engraftment); Early phase (30-100 days, after engraftment); Late phase (>100 days). A normal chest radiograph does not exclude infection in immunocompromissed patients with respiratory symptoms; further assessment with chest CT should always be considered in order to detect subtle imaging abnormalities. Infectious bronchiolitis manifesting with centrilobular nodules and diffuse ground-glass opacities on CT is commonly seen in immunocompromised patients.