Computed tomography in the diagnosis of central nervous system lymphomas.

CT appearances of 13 patients diagnosed as having CNS lymphoma were reviewed. Eight patients were of primary type and 5 patients had secondary CNS involvement. In primary CNS lymphoma, the median age was 62.5 years. All except one were male. Solitary lesions were observed in 4 patients; multiple lesions in 3 patients and an infiltrative lesion in one. Characteristic CT finding was a hyper-or isodense mass with homogeneous enhancement in the gray matter and corpus callosum. In secondary CNS lymphoma, the median age was 30 years. Two had solitary lesions. Isodense lesions were found in 4 of 5 patients.