Central Nervous System Lesions in Immunocompromised Patients

Immunodeficiency can affect different components of the immune system and predispose to different types of opportunistic infections. For example, a defect in neutrophil or humoral immunity increases risk from disseminated infection by extracellular pathogens, whereas a defect in cytotoxic activity by natural killer cells or CD8(+) T lymphocytes increases risk from intracellular pathogens. The latter also increases risk from malignancies, due to impairment of normal immunosurveillance against abnormal neoplastic cells. The purpose of this article is to discuss central nervous system lesions that may be seen in the immunocompromised patient, organized into 5 categories: bacterial, fungal, parasitic, viral, and neoplastic.