[Neuropathologic evaluation of intrathecal prophylaxis results in adults with high grade non-Hodgkin's lymphomas].

The influence of the intrathecal methotrexate (IT MTX) prophylaxis on frequency and intensity of lymphomatous infiltrates within the leptomeninges and spinal roots in adults with non-Hodgkin's lymphomas (HGNHL) of high grade malignancy was evaluated. The effect of selected risk factors on the central nervous system (CNS) involvement by infiltrates was also analysed. Based on the results, indications for the prophylactic management were discussed. The post-mortem neuropathological investigations have been performed on 42 deceased patients having the NHL of high grade malignancy, treated and suffered in the Department of Haematology of the Pomeranian Medical Academy between 1980-1994. In all patients, neither apparent neurological complications nor changes in the cerebrospinal fluid during the disease were noted. Generally, lymphomatous infiltrates within the leptomeninges and spinal roots were observed in 64 per cent of cases. They were usually observed as variously sized foci: from single small to large, diffused in many regions. The study group of 21 patients subjected to IT MTX prophylaxis were compared with 21 patients without "CNS prophylaxis" (control group). Frequency and intensity of lymphomatous infiltrates decreased significantly after more than 3 IT MTX injections (Tab. 1) within spinal leptomeninges only (Tab. 2, 3). No benefits of this kind of treatment within cerebellar leptomeninges were noted. A poor penetration of the MTX (given by lumbar injection) into this region, could be a possible explanation of such result. It was disclosed that high white blood cells (WBC) count was the most important risk factor of the CNS involvement by lymphomatous infiltrates. Frequency of lymphomatous infiltrates diminished after IT MTX prophylaxis only in patients with WBC count less than 50 G/1 during the disease (Tab. 4). It was also found that lymphomatous infiltrates within the leptomeninges and spinal roots occurred in high percentage in both groups, and were independent of histological type of the HGNHL (Tab. 5) as well as of patients' age. From the neuropathological point of view, IT MTX prophylaxis seems to be ineffective in patients with the HGNHL, who did not reach a complete heamatological remission. A complete elimination of lymphomatous cells from the intracranial leptomeninges is particularly difficult to achieve. Considering the fact that it is hard to foresee response to polychemotherapy, especially at the beginning of the treatment, and--as present study shows--the lymphomatous infiltrates in the CNS are frequently found soon after the onset of the disease, "CNS prophylaxis" should be initiated simultaneously with the induction of remission. However, the continuation of the prophylaxis without haematological control of the disease seems to be aimless.