Histopathology

During the last 30 years, advances in intensive and critical care units, organ transplantation, concomitant use of immunosuppressive drugs, and increasing prevalence of chronic diseases, malnutrition, and other debilitating conditions, as well as the human immunodeficiency virus pandemic, have increased the incidence of systemic mycotic diseases, the most serious form of fungal diseases are the ones that comprise the central nervous system, representing the most dangerous clinical situations. In those cases, starting an adequate therapy through a rapid and assertive diagnosis is absolutely necessary. Considering the fastidious microbiological nature of some fungi (longtime requirement, specific culture conditions, and biohazard issues), as well as the lack of alternative testing availability, a rapid diagnosis is always challenging. When a tissue or liquid specimen is available, its pathological analysis constitutes a rapid and cost-effective way to provide a presumptive or definitive diagnosis of an invasive fungal infection; however, microbiologists, pathologists, and clinicians need to be aware of the limitations of microscopical diagnosis. In this chapter, we review the usual histological presentation of the most frequent central nervous system fungal infections.