Computed tomography of malignant lymphoma of the brain.

Correct diagnosis of malignant lymphoma of the brain and differentiation from malignant glioma, metastases, meningeoma and infection is often difficult. With the aim of finding characteristics pointing to the correct diagnosis all CT examinations from 16 patients with primary or secondary lymphoma of the brain were analysed. In 3 of 10 patients with primary lymphoma and 4 of 6 with secondary lymphoma the tumors were multiple. No differences between the CT appearance of primary and secondary lymphoma were found except that secondary lymphomas were generally smaller and more often multiple. The lymphomas were most often well demarcated, had a density equal to or slightly higher than normal brain tissue, were surrounded by no or slight edema and showed a moderate to marked contrast enhancement. The tumors were situated in the basal ganglia, corpus callosum or cerebellum in high frequency and were always in contact with either the ependyma of the ventricles or the superficial subarachnoid space. A tumor with widespread infiltration of the surroundings of the ventricles seen in 6 patients in the material is highly characteristic of lymphoma.