Lymphoreticular proliferative disorders of the CNS and other organs: analogies and differences

Authors review differences between CNS and extraneural reticuloses, and consider the immediate threat to life by CNS lymphomas contrasting to other organ lymphomas, which usually become fatal only after generalization. Other special features of CNS reticuloses include the role of microglial cells, reactive astrocytosis, variations in meningeal vs. parenchymatous involvement and easier morphologic confusion with inflammatory processes. Analogies exist between CNS and extranodal "organ" lymphomas in terms of relatively late or no generalization. The entire spectrum of lymphomatous and histiocytic proliferation may occur in the CNS, the latter including atypical fibrous xanthomas and xanthosarcomas. A further analogy is seen in the presence of lymphocyte and plasma cells in cerebral and organ lymphomas that may well represent host defense reaction. When present in large numbers they may be responsible for the "inflammatory" appearance of some reticulum cell sarcomas of the brain.