Secondary involvement of the central nervous system in malignant non-Hodgkin's lymphoma. A study of 30 cases in a series of 498 patients.

Of 498 patients with non-Hodgkin's lymphoma (NHL), 30 showed secondary central nervous system (CNS) involvement. Of these 30 patients, 26 had high-grade malignancy and 21 lymphoblastic lymphoma, mainly convoluted (n = 8) or Burkitt (n = 6) type according to the Kiel classification. In half of the 30 patients, CNS involvement was associated with progressive lymphoma. Bone marrow involvement was found in half of the patients before or at the time of the diagnosis of CNS involvement, which was 12 months (mean) after the diagnosis of NHL. Eight patients received CNS prophylaxis. Results of treatment for CNS involvement are poor (mean survival time from CNS involvement: 3.5 months). The Kiel classification allows good identification of patients at high risk of CNS lymphoma: systematic CNS prophylaxis is indicated only in the convoluted and Burkitt types. An efficient prophylaxis must be found and results must be confirmed by other studies.