[Diagnosis of primary non-Hodgkin lymphomas of the central nervous system].

In literature, primary malignant lymphomas (PML) of the central nervous system (CNS) have been known for many years under different names, although diagnosis was almost exclusively made via autopsy. It is only since the existence of computed tomography (CT) that there is a possibility of identifying or at least presuming intra vitam such malignancy and of securing the diagnosis via brain biopsy. This is most important because it enables an early treatment of patients by means of radiation and chemotherapy. We are documenting a new approach to identify the PML of CNS by four case histories of our own patients. This consists in the specific manner in which these tumours react to high doses of corticosteroid therapy. Under this treatment they diminish in size or even disappear completely. This can even be seen in other diseases, but when such behaviour of an intracerebral lesion is seen in a CT scan it should be of help in the evaluation of differential diagnosis and should be regarded as an important pointer towards achieving early diagnosis of PML of the CNS.