Immunoperoxidase study of primary central nervous system lymphomas.

Primary central nervous system (CNS) lymphomas have been perceived as CNS counterparts of systemic non-Hodgkin's lymphomas (NHL). Their pathogenesis in respect to the cell of origin, however, has been controversial. A highly sensitive and specific immunoperoxidase method for cytoplasmic immunoglobulins (CIg) using anti-kappa and anti-lambda light-chain antisera in addition to antibodies against IgM, IgG, IgA and IgE heavy chains and J-chain was performed on 27 surgically removed and histologically confirmed primary CNS lymphomas. In order to increase the sensitivity, slides were treated with trypsin to expose the various CIg components. Results indicated that the majority of CNS lymphomas (20 cases or 74.01 percent) were negative for monoclonal CIg. Only four cases (14.81 percent) were definitely positive for CIg with monoclonal staining pattern. Results of the remaining three cases were inconclusive. Among those four cases with positive CIg, three were histologically identified as immunoblastic sarcomas according to the Luke-Collins classification. It is concluded that, in contrast to systemic NHL, primary CNS lymphomas are mostly negative for monoclonal CIg. Whether these CIg negative neoplasms are T and/or null cells in nature or whether they represent an unidentified group of neoplasms is not clear at the present.