Central nervous system lymphomas. Immunohistochemical and clinicopathologic study of 26 autopsy cases.

Twenty-six malignant lymphomas involving the central nervous system were studied. Eleven were primary (P) and 15 were systemic (S). Eight cases (3 P, 5 S) occurred in immunocompromised patients. Age at presentation in immunocompromised patients was typically younger than in the nonimmunocompromised patients. Presenting complaints of central nervous system involvement included headache, seizures, personality changes, memory lapses, ataxia, cranial nerve symptoms, and impaired consciousness. Cerebrospinal fluid involvement was seen only in 3 S cases. In 8 of the P cases, the diagnosis was first established at autopsy; in 6 of the S cases, central nervous system involvement was first documented at autopsy. Survival was longer in treated patients than in those who received no therapy (5 months in P cases and 9.3 months in S cases; 2.3 months without therapy). Regardless of therapy, the average survival of immunocompromised patients was 2.4 months. The majority of cases were multifocal. Of the P cases, 1 was of low histologic grade, 9 were of intermediate grade, and 1 was of high grade. Of the S cases, 5 were of low grade, 9 were of intermediate grade, and 1 was of high grade. Immunophenotypic studies were performed on formalin-fixed, paraffin-embedded tissue with antisera against common leukocyte antigen (all reactive), B-cell markers (L26, MB2, LN1, and LN2), T-cell markers (UCHL1 and MT1), Leu-M1, Leu-7, and HLA-DR (LN3). Two S cases were of T-cell phenotype; all others were of B-cell derivation. Eleven cases were HLA-DR positive (all of B-cell phenotype). One T-cell lymphoma was reactive for Leu-7. All cases were nonreactive for Leu-M1. All cases in immunosuppressed patients and all P cases were of B-cell phenotype.