CORRELATION OF HISTOPATHOLOGY OF BRAIN TUMORS TO THEIR PROGNOSIS

Abstract

The prognosis of CNS neoplasms depends largely on histologic type and degree of malignancy. The overall survival rate for CNS primary cancer in SEER data, USA, is 27.5%. However survival is markedly influenced by tumor type and grade (Ries, 1994) The WHO classification (1993) categorized brain tumors according to their presumed cell of origin into tumors of neuroepithelial tissue, embryonal tumors, tumors of meningeothelial cells, germ cell tumors, tumors of sella region and tumors of uncertain etiology as haemangioblastoma. Tumors of neuroepithelial tissue include gliomas, choroid plexus tumors, pineal body tumors and . neuronal tumors. Embryonal tumors include medulloblastoma, cerebral neuroblastoma, ependymoblastoma & primitive neuroectodermal tumors. Germ cell tumors include germinoma, embryonal carcinoma, endodermal sinus tumor, choriocarcinoma, teratoma & mixed germ cell tumor. (Kleihues, et al., • I 1993). I I Astrocytic tumors are subclassified into 2 categories. The first category I comprises astrocytoma and its variants: fibrillary, protoplasmic, I gemistocytic & anaplastic. These are biologically aggressive tumors of a I I relatively high proliferative potential .The second category, comprised of ! rather benign tumors of a limited proliferative capacity and reasonable good prognosis, includes as pilocytic astrocytoma, pleomorphic xanthastrocytoma and subependymal giant cell astrocytoma • of tuberous sclerosis.(Kleihues et al., 1993). Some of the features of a pilocytic astrocytoma such as microcysts and very low cell density were shown to have a positive effect on prognosis. These features also have an acceptable degree of reliability (Gilles et al., 1994). Mitotic activity has long been used as an indicator of very actively proliferating tumors and so would have been expected to have had an adverse effect on prognosis (Daumas et al., 1988).