Encephalitis with Nondiagnostic Brain Biopsy: What Did They End Up Having?

Encephalitis, not otherwise specified (ENOS), represents a nondiagnostic brain biopsy in cases of rapid clinical deterioration when the cause is unknown. To examine what further testing and follow-up can reveal in such cases, researchers reviewed outcomes in 58 cases of ENOS (median age, 40 [interquartile range, 23–52]; 22% with HIV).

The investigators' additional review and immunohistochemical analyses of the pathologic material from 29 patients led to a more specific diagnosis in 34%, including demyelinating disease, progressive multifocal leukoencephalopathy, glioma, lymphomatoid granulomatosis, ischemia, mesial temporal sclerosis, and lymphoma. For those who had additional follow-up and testing, diagnoses included tuberculosis, herpes si…