Primary intracerebral small lymphocytic non-Hodgkin's lymphoma with plasmacytoid differentiation, associated with prominent extracellular proteinaceous deposits.

A case of primary intracerebral non-Hodgkin's lymphoma in a 67-yr-old immunocompetent female is presented. The histopathological diagnosis was supported by immunohistochemical, flow cytometric and electron microscopic findings, and by clinical staging. This tumor is unusual in its morphological features of a low grade, small lymphocytic lymphoma with plasmacytoid differentiation (Working Formulation Classification), and its association with extensive, local, extracellular, proteinaceous deposits. Primary central nervous system non-Hodgkin's lymphomas are briefly discussed and it is postulated that the extracellular proteinaceous deposits in this case originated from immunoglobulins secreted by the neoplastic cells. To our knowledge the massive degree of local immunoglobulin deposition present in this primary central nervous system lymphoma has not been previously reported in the literature.