WT1 Expression in Reactive and Neoplastic Glial Cells as a New Diagnostic Tool

Abstract

Glial tumors are the most common primary brain tumors. They are derived from astrocytes, oligodendroglial cells, and ependyma. The majority of glial tumors are malignant. The aim of our study is to evaluate retrospectively the immunohistochemicalexpression ofWT1in reactive and neoplastic glial cells. The material ofthisstudy included 55 cases of brain biopsies, 45 cases of which were previously diagnosedas glial tumors(astrocytomas, oligodendrogliomas and ependymomas) and 10 cases as reactive brain tissue. The cases were received at the PathologyDepartment of Ain Shams University Hospitals during the period (2006-2011). All cases were subjected to the following:Clinical studies by reviewing the files of the patients regarding age, sex and type of specimen. Histopathologicalre-examination ofH& E stained sections prepared from paraffin blocks at 5µ thickness. Immunohistochemical staining of paraffin embedded tissue sections for WT1 and assessment of the stained slides. Glioblastomawas the most common astrocytic tumor in our study representing 36% of astrocytic tumors. As regards the age of patients in this study, the mean age of studied cases was 41.8 years. As regards sex incidence, slight male predominance was detected representing 51% withM:F ratio 1.1:1. As regards site of predilection most of cases were located in the cerebral cortex representing 75% followed by intraventricularand posterior fossa cases. The histopathological results revealed 10 cases of gliosisrepresenting (18.2 %),38 cases of astrocytic tumors (69.1 %), 3 cases of oligodendroglioma (5.5%), while 4 cases of ependymoma. The 38 cases astrocytomas included glioblastoma (grade IV) which was the most common grade representing(52.6%) of astrocytomas, followedbyanaplastic astrocytoma grade III representing 18.4%, thenDiffuse astrocytoma grade II representing15.8 %.The least common was pilocytic astrocytoma grade Irepresenting 13.2 %. Two cases of oligodendrogliomawere grade II(66.7%)and(33.3%) was grade III. Three cases ofependymoma were grade II (75%) andone case was grade III (25%). As regards the immunohistochemical studies, negativity of WT1 was detected in all of the 10 casesofgliosiscases and positivity of WT1 was detected in all theglial tumor cases (45/45, 100%). The intensity of staining for WT1 was mild (score 1) in 11/45 cases representing 24.4%, moderate (score 2) in 12/45 cases representing 26.6%, marked (score 3 and 4) in 22/45 cases representing 48.8 %. There was a lower mean age among patients with WT1 score 1 compared to other groups with higher WT1 score(p value=0.001).As regarding gender, there was no significant