Cerebral Pseudallescheria boydii infection: unique occurrence of fungus ball formation in the brain.

Pseudallescheria (Petriellidium) boydii is the most frequent etiologic agent of mycetoma in temperate regions of the world. In addition, it may also occur as a systemic infection in immunocompromised patients. Infection of the central nervous system is rare, and only eleven cases of Pseudallescheria brain abscess have been documented. We report a leukemic patient in whom disseminated pseudallescheriasis was diagnosed only after death. This case is unique in that a white matter cavitation was present containing a fungoma of Pseudallescheria, the first report of a cerebral fungus ball caused by this organism. The previous cases of Pseudallescheria brain abscess are reviewed, and the histopathologic features of Pseudallescheria which permit its differentiation from Aspergillus and other fungi are discussed.