35-year-old HIV-positive woman with Basal forebrain mass.

A 35-year-old African American woman with HIV/AIDS presented with altered mental status. A CT of the head revealed an infiltrating hypodense intra-axial mass within the basal forebrain. Lumbar puncture showed a lymphocytic pleocytosis, elevated protein and low glucose. PCR analysis of the CSF was negative for Mycobacterium tuberculosis, HSV, VZV, CMV and JC virus. There was low positivity for EBV DNA. Serologic studies were consistent with past infections with EBV and CMV and were negative for toxoplasmosis, histoplasmosis, Cryptococcus and West Nile virus. VDRL was non-reactive. CSF and blood cultures were negative. She soon expired. Post-mortem examination of the patient's brain showed a poorly delineated area of softening and hemorrhage within the basal forebrain. Histologic examination revealed necrotizing encephalitis with perivascular lymphocytes and glial cells with numerous cytoplasmic and intranuclear inclusions. Immunohistochemistry was strongly positive for adenovirus and negative for HSV, CMV, SV40 and EBV. Electron microscopy confirmed the presence virions consistent with adenovirus. We conclude that adenovirus is a rare and sometimes unsuspected cause of encephalitis that may present as a forebrain mass lesion.