Correlations between cytologic composition and biologic behavior in the glioblastoma multiforme. A postmortem study of 50 cases

The brains of 50 adults with supratentorial glioblastoma multiforme were studied post mortem. The cytologic compositions of the neoplasms were examined in each of three sites: (1) in and around the original tumor bed; (2) zones of infiltration of contiguous structures; and (3) implants in the subarachnoid and/or ventricular spaces. For this purpose, six different cell types were defined: small anaplastic cells (SAC), small fibrillated cells (SFC), fibrillated astrocytes (FA), pleomorphic astrocytes (PA), gemistocytic astrocytes (GA), and large bizarre cells (LBC). In 16 cases with marked mass effect in the original tumor bed entirely due to the neoplasm, the cytologic composition of the neoplasm was predominantly SAC (14 cases) and SFC (2 cases). The prevalence of these two cellular types was evident in the infiltrated regions in 36 of 42 cases, and in the metastatic foci of 11 of 13 cases. In 10 of 11 cases in which there was mild or no mass effect, only limited infiltration in the ipsilateral hemisphere, and no metastases, the neoplasms were composed of a combination of FA, PA, GA, and LBC. The observations suggest that, in spite of the glioblastoma's cytologic heterogeneity, the pathologic substrate of aggressiveness in this malignant glioma is related largely to the proliferation of a population of small anaplastic cells. On the basis of this observation, as well as the consideration of certain clinical and therapeutic variables, an outline is presented summarizing the history of the glioblastoma multiforme from treatment until the time of death.