Absence of contrast enhancement on CT brain scans of patients with supratentorial malignant gliomas.

The medical records of 229 consecutive patients with supratentorial malignant gliomas were reviewed with respect to histology, age at diagnosis, tumor location, and enhancement pattern on the CT obtained after the administration of contrast material at the time of operation. Nonenhancing tumors were identified in four (4%) of 93 patients with glioblastoma multiforme (GM), three (30%) of ten with gemistocytic astrocytoma (GA), 23 (31%) of 74 with highly anaplastic astrocytoma (HAA), and 28 (54%) of 52 with moderately anaplastic astrocytoma (MoAA). The age-related incidence of the various glioma histiotypes (both enhancing and nonenhancing) was reflected by the median age at diagnosis: 50 years in GM, 52 years in GA, 40 years in HAA, and 34 years in MoAA. The age and CT contrast enhancement pattern were similar in patients with GM, GA, and MoAA; patients with nonenhancing HAAs tended to be younger at presentation. The tumor location and the frequency of enhancing and nonenhancing lesions were similar for all groups except MoAA, in which nonenhancing tumors were most often frontotemporal and enhancing tumors were usually frontoparietal. Our results demonstrate that it is important to obtain histologic confirmation of the diagnosis in patients with supratentorial gliomas regardless of the presence or absence of contrast enhancement of the tumor on CT, because neither of these characteristics correlates with the tumor histology.