Glioblastoma multiforme masquerading as a tumefactive demyelinating lesion: Lessons learned at autopsy.

Tumefactive demyelinating (TD) lesions are extremely challenging lesions to diagnose during their histopathological examination and are often misdiagnosed as tumors. On the contrary, a glioblastoma multiforme is rarely misdiagnosed as a TD unless the two coexist. We present a case of a 60-year old man who was diagnosed as having tumefactive demyelination on a stereotactic biopsy. At autopsy, however, the lesion revealed a grade IV glioblastoma. The myelin loss along the periphery of the lesion was erroneously interpreted as TD during the histopathological examination. We have described the imaging, the biopsy, and the autopsy findings of this instructive case. It is pertinent to recognize its histology to prevent a misdiagnosis.