title: WT1 is not a reliable marker to distinguish reactive from neoplastic astrocyte populations in the central nervous system.
abstract: A diagnostic difficulty in neuropathology practice is distinguishing reactive from neoplastic astrocyte populations. This is particularly true in small biopsy samples that lack evidence of increased cellularity or mitotic activity, microvascular proliferation, or necrosis. We performed the current study to validate the previously reported finding that in the central nervous system, the expression of WT1 is limited to neoplastic astrocytes. We retrospectively studied WT1 protein expression by immunohistochemistry (IHC) in 100 formalin-fixed, paraffin-embedded brain tissue samples consisting of 3 normal control tissues, 44 cases of reactive gliosis, 49 gliomas and 4 lesions suspicious for glioma. In normal human cortex, WT1 staining was restricted to vascular endothelium. Most cases of reactive gliosis (82%) showed at least focal WT1 positivity, and analysis of specimens with electrode monitoring lesions showed an inverse relationship between WT1 expression intensity and the number of days from electrode placement to tissue resection. All glioma samples (100%) and all cases suspicious for glioma (100%) showed at least focal WT1 positivity. Our results likely differ from those in the prior report because of differences in tissue fixation and IHC methodology. Thus, our findings indicate that WT1 expression alone is not a reliable feature to distinguish reactive from neoplastic astrocytes.
authors.affiliation: Department of Pathology (Neuropathology), University of Virginia School of Medicine, Charlottesville, VA 22908, USA. tdb5b@virginia.edu
authors.forename: T David
authors.initials: TD
authors.lastname: Bourne
authors.forename: W Jeffrey
authors.initials: WJ
authors.lastname: Elias
authors.forename: M Beatriz S
authors.initials: MB
authors.lastname: Lopes
authors.forename: James W
authors.initials: JW
authors.lastname: Mandell
mesh_terms: D001253:Astrocytes / Q000378:metabolism*; D001921:Brain / Q000378:metabolism / Q000473:pathology*; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000473:pathology; D004566:Electrodes; D004827:Epilepsy / Q000473:pathology / Q000503:physiopathology; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005910:Glioma / Q000175:diagnosis* / Q000378:metabolism; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D013223:Statistics as Topic; D025721:WT1 Proteins / Q000378:metabolism*
chemical_list: D005904:Glial Fibrillary Acidic Protein; D025721:WT1 Proteins