Primary intracranial CNS lymphoma: MR manifestations

We reviewed MR scans of 10 patients with biopsy-proved primary CNS lymphoma. Twenty-five lesions were identified in 10 patients (four with AIDS and six without AIDS). In general, the typical lesion of CNS lymphoma was found to have the following MR characteristics: they were slightly hypointense on n-weighted images and slightly hyperintense on proton density and T2-weighted images relative to gray matter; they induced mild edema and mild to moderate mass effect. In AIDS patients, 82% of the lesions were smaller than 2 em in diameter, and were frequently located in the temporal lobes and basal ganglia; they were often multiple. In non-AIDS patients, 75% of the lesions were larger than 2 em in diameter and were primarily found in the deep parietal lobe; most were solitary. Primary CNS lymphoma is a relatively rare occurrence and , despite the recent increase in AIDS patients, it represents less than 1 .5% of all CNS neoplasms MR imaging is an effective · method for demonstrating a variety of intracranial abnormalities and provides superior contrast resolution to CT. The literature includes only a few references to intracranial lymphoma visualized with MR [9-12]. The described signal intensities of these lesions range from hypo-to isointense relative to gray matter on T1-weighted images and intensity is even more variable on T2-weighted images. This article describes more fully the spectrum of MR findings in primary CNS lymphoma. Subjects and Methods We evaluated 10 patients with biopsy-proved primary CNS lymphoma Four patients presented with AIDS; the remaining six patients had no preexisting immunocompromising disease. In all patients, the CSF titers and stereotactic brain biopsy were negative for infectious diseases. Although the negative CSF and brain biopsy do not entirely exclude the coexistence of lymphoma with an opportunistic fungal , viral, or protozoan infection, there was no clinical or laboratory evidence to suggest dual pathologies . In patients with one lesion, the shortest and safest pathway for stereotactic biopsy was chosen . In the four patients with multiple lesions , only the lesion most easily reached was biopsied . Biopsy sites included the parietal, temporal , frontal , or occipital lobe; basal ganglia; thalamus