The Immunocompromised Patient: AIDS

Acquired immune deficiency syndrome (AIDS) is caused by infection with human immunodeficiency virus (HIV) that results in decreased immunity and favors infectious or neoplastic conditions. The onset of clinical AIDS is defined by a CD4 count of less than 200 cells/mm3 or CD4 cells < 14% of all leukocytes in an HIV-positive patient, even in the absence of opportunistic infections. Imaging abnormalities in HIV(+) should be correlated with the CD4 count to narrow the differential diagnosis. Diffuse ground glass opacities (GGO) on CT in a patient with AIDS and hypoxemia, is virtually diagnostic of Pneumocystis pneumonia (PCP). CT is indicated in HIV(+) patients with respiratory symptoms and normal chest radiographs. Suspect tuberculosis (TB) in patients with advanced AIDS and low CD4 counts presenting with consolidation and lymphadenopathy. Kaposi sarcoma (KS) may simulate cardiogenic pulmonary edema on imaging and should be suspected in patients without clinical evidence of edema.