Tumefactive demyelination and glioblastoma: a rare collision lesion

Inflammatory demyelination occasionally forms a solitary mass lesion clinically and radiographically indistinguishable from glioma, replete with enhancement and mass effect. Termed "tumefactive demyelination" it often prompts a brain biopsy.

We undertook neuroimaging and morphologic analysis of a unifocal demyelinating lesion intimately associated with glioblastoma. MRI characteristics of the lesion were assessed as were biopsy and resection specimens by both histological and immunohistochemical methods.

The patient, a 49-year-old woman, presented with subacute onset headaches. An MRI T1W scan revealed a hemispheric mass with centrally reduced signal and ring enhancement. T2W images showed increased central signal with a rim of reduced signal co-localized to the enhancing ring. A biopsy was initially misinterpreted as demyelination alone, given abundance of histiocytes, the presence of hypertrophic astrocytes with micronuclei ("Creutzfeldt-Peters cells"), and occasional mitoses. Upon consultative review, two histologically distinct components, one inflammatory demyelination and the other an anaplastic astrocytoma were revealed. Subsequent complete resection of the abnormality demonstrated a WHO grade IV astrocytoma (glioblastoma multiforme).

Our experience underscores the importance of adequate tissue sampling during biopsy for suspected glioma, and confirms the fact that active inflammatory demyelination may coexist with a high-grade glioma. Despite detailed study, the basis for the association remains elusive.