EPITHELIAL DIFFERENTIATION IN GLIOMAS, MENINGIOMAS AND CHOROID-PLEXUS PAPILLOMAS

The immunohistological findings using antibodies to different intermediate filaments (glial fibrillary acidic protein, vimentin and two types of cytokeratin) and epithelia membrane antigen are described in 89 gliomas, 19 meningiomas and 8 choroid plexus papillomas (CPPs) from adult patients. All the patients had total or subtotal surgical excision of their tumours with clinical follow up for between 3 and 7 years. The immunohistological results were correlated with the histological features and patient survival. Tumours other than low grade astrocytomas, oligodendrogliomas and anaplastic ependymomas expressed one or more epithelial markers. This immunohistological evidence of epithelial differentiation in the absence of histological epithelial features in gliomas confirms that the two are not necessarily correlated. It is concluded that the expression of epithelial markers in some intradural tumours may reflect aberrant differentiation related to the degree of anaplasia in poorly differentiated astrocytomas and glioblastomas. All the patients with anaplastic epithelial marker-positive gliomas died within 1 year, whereas only 68% of patients with marker-negative tumours died within the follow-up period. In ependymomas and meningiomas, the expression of epithelial markers may reflect their histogenesis, while in malignant CPPs such expression could denote either their aberrant differentiation or histogenetic derivation.