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The purpose of this study was to determine whether apparent diffusion coefficient (ADC) value and T2 signal intensity (SI) in primary brain lymphomas affect their SI on diffusion-weighted images (DWI). On DWI of 16 brain lesions of 16 patients, 9 (56.2%) were hyperintense (grade-3), 4 (25%) partially hyperintense (grade-2) and 3 (18.8%) isointense (grade-1). The mean ADC value of grade-3 lesions was significantly lower than of grade-1 lesions ( p = 0.028). The grade-1 lesions had ADC values of more than 0.8 and contrast-to-noise ratios of less than 18 on T2-weighted images. Their ADC value and T2 signal intensity affect their SI on DWI.

To determine if water diffusivity within lymphomas and high-grade astrocytomas correlates with cellularity.Echo-planar diffusion-weighted magnetic resonance (MR) images obtained in 11 patients with brain lymphomas (19 lesions) and in 17 patients with astrocytomas (19 lesions) were retrospectively reviewed. Regions of interest were drawn on apparent diffusion coefficient (ADC) maps in enhancing tumor. ADC values were normalized by dividing ADC values of tumors by those of normal-appearing regions and expressing the quotient as a ratio. Histologic samples from 11 patients with astrocytomas (11 lesions) and seven patients with lymphoma (seven lesions) were reviewed. Cellularity was measured by calculating the percentage of nuclear area and the percentage of cytoplasmic area and expressing the results as the nuclear-to-cytoplasmic (N/C) ratio. The ADC and N/C ratios of both tumor types were compared by using a two-tailed t test.Mean ADC ratio of lymphomas was 1.15 (SD, 0.33; standard error of the mean [SEM], 0.10), and that of high-grade astrocytomas was 1.68 (SD, 0.48; SEM, 0.11) (P.01). Mean N/C ratio of lymphoma was 1.45 (SD, 0.94; SEM, 0.36), and that of high-grade astrocytomas was 0.24 (SD, 0.18; SEM, 0.05) (P.01).Measurements of water diffusivity and cellularity suggest that higher cellularity contributes to more restricted diffusion.

After lagging behind other brain tumor disciplines in the 1980s, the epidemiology of brain tumors is now making progress on several fronts. The Central Brain Tumor Registry in the USA has made a complete description of primary brain tumors available to researchers. International data suggest that environmental components in the etiology of brain tumors are likely to be widely dispersed by geography and demographic subgroups. There are few proven causes of brain tumors: high-dose ionizing radiation, inherited genetic syndromes and AIDs-related brain lymphomas. Promising avenues of research include the role of immune function, genetic components in families, metabolic and DNA-repair pathways and neurocarcinogen exposures.

The management of malignant primary brain tumours consists in a combination of surgery, radiation therapy and chemotherapy. The specific roles of each treatment modality will be reviewed by tumour type: Gliomas, including malignant and low-grade gliomas, oligodendrogliomas and ependymomas; Medulloblastomas; Primary brain lymphomas.

Nine primary malignant lymphomas of the central nervous system in non-AIDS patients were studied. Neuroradiological and histological appearances and immunophenotyping are reported. No correlation was found between the radiological appearances and the histological classification.

Certain central nervous system tumours (C.N.S.) can prove difficult to diagnose by conventional histological techniques. We have evaluated the use of monoclonal antibodies as adjuncts to tumour diagnosis using a panel of such reagents. This type of analysis has enabled rapid and accurate diagnosis to be made, even in situations where standard techniques have proved equivocal. We have been able to confidently distinguish gliomas, meningiomas, medulloblastomas, choroid plexus tumours, neuroblastomas, various metastatic carcinomas and primary brain lymphomas on the basis of the characteristic antigen profile expressed by each of these tumours.

A post-mortem study of 17 AIDS-related brain lymphomas was carried. These were B-cell lymphomas of the immunoblastic-type. They expressed activation and adhesion markers, and EBV latent gene products.