THE VARIABLE MR APPEARANCE OF PRIMARY LYMPHOMA OF THE CENTRAL-NERVOUS-SYSTEM - COMPARISON WITH HISTOPATHOLOGIC FEATURES

PURPOSE: To describe the MR features of primary central nervous system (CNS) lymphoma and to determine whether there is a correlation with h istopathologic findings. METHODS: The MR images, pathologic specimens, and clinical records of 23 patients with primary CNS lymphoma were re viewed. The imaging and pathologic characteristics were tabulated and compared by using the standard tests for association in a two-dimensio nal contingency table. RESULTS: A total of 61 lesions were present in 23 patients; 12 patients (52%) had multiple lesions. All lesions were isointense or hypointense on T1-weighted images, and 53% were isointen se or hypointense on T2-weighted images. Twenty patients received intr avenous contrast material, and 43 (91%) of 47 lesions enhanced. The th ree patients who had nonenhancing lesions received steroids before the initial MR studies. Enhancement patterns differed between the immunoc ompetent and the immunocompromised hosts, with the latter group harbor ing a higher percentage of rim-enhancing lesions. Twenty-seven (44%) o f the lesions were centered in a cerebral hemisphere and 14 (23%) were centered in the central gray matter. There was a statistically signif icant correlation between a higher degree of necrosis histologically a nd hyperintensity on T2-weighted MR images. The degree of necrosis als o showed a positive correlation with rim enhancement. CONCLUSIONS: Pri mary CNS lymphoma has a variable MR appearance that correlates with th e severity of intratumoral necrosis. These imaging characteristics, as well as lesion location, mean lesion size, and proclivity to harbor n ecrosis, are altered in the immunocompromised host.