Abstract
Abstract only Coccidioides ssp. is a parasitic dimorphic fungus predominantly found in the western and southwestern regions of the United States. The spherule form of this opportunistic organism is responsible for a host of tissue infections in humans, most commonly pneumonia. CNS involvement by coccidioides is an uncommon but well recognized complication, typically manifesting as basilar meningitis. The hyphal form, which existsts naturally in soil, is rarely diagnosed in human infections. Most case reports note infection with the hyphal form only in oxygenated tissues such as lung or osteomyelitic sinus tracts. There are only very rare reports of the hyphal form in the CNS and always in association with aerated surgical devices. We report a coccidioides meningitis and mycotic anyseursm of the basilar artery in a 24‐year‐old pregnant female with a history of HIV. Histologic examination of GMS‐stained sections showed numerous branching hyphae, arthrospores and occasional spherule forms, admixed with amultinucleated giant cells and acute inflammation. Microscopic granulomas were also seen in the subarachnoid space distributed in a military pattern. We believe this to be one of the first reports of a coccidioides ssp. infection with prevalent hyphae forms in the nonoxygenated CNS.