[Immunohistochemical study in 16 cases of primary lymphoma of the central nervous system (author's transl)].

Sixteen primary lymphomas of the central nervous system (CNS) have been studied with an immunoperoxidase technique (PAP) for the demonstration of intracytoplasmic immunoglobulins. The material was obtained by biopsy (10 cases) and at autopsy (6 cases). For comparison, ten other tumors (glial tumors and secondary lymphomas involving the nervous tissue) were simultaneously investigated. In the 16 primary lymphomas, 14 contained intracellular immunoglobulins that were considered "monoclonal" in 9 cases, "probably monoclonal" in 4 cases but "uninterpretable" in the last one. According to the Kiel classification, the 13 malignant lymphomas with intracellular immunoglobulins were classified, morphologically, as immunoblastic sarcomas (9 cases) or immunocytomas (4 cases). No immunoglobulins were detected in 2 cases: 1 lymphoblastic lymphoma and 1 centrocytic lymphoma. Various amounts of intracytoplasmic immunoglobulins were detected in inflammatory cells and glial cells (either reactive or tumoral) but the pattern of staining was consistent with current concepts of polyclonality. Therefore, a diagnosis based on the Kiel classification of lymphomas and the PAP technique will allow a more accurate prognosis on the evolution of primary lymphomas of the CNS with aspect of "high grade" and "low grade" malignancy.