Central nervous system lymphoma: histologic types and CT appearance.

The distribution of histologic types of lymphoma according to the proposed working formulation was determined for 55 patients with primary central nervous system (CNS) non-Hodgkin lymphoma. Fifty-five percent of these patients had diffuse large-cell histologic features. When the relationship between histologic type and computed tomographic (CT) appearance was analyzed, the following trends were noted: A greater percentage of mixed cell tumors were multiple when compared with other types; noncleaved small-cell tumors were more commonly located in the central gray matter or corpus callosum than were other types; all immunoblastic tumors were enhanced homogeneously, unlike other types; and smaller tumors appeared to be associated with an increased histologic grade. Eleven patients had CT confirmation of a CNS recurrence; in eight patients, the recurrent tumor was in a different location than the original lesion. Eleven patients had associated intraocular lymphoma, and four were immunosuppressed.