[Malignant and benign lymphomas: histologic classification and immunomorphologic studies. Results of 838 cases].

800 malignant (22.9% Hodgkin's, 77.1% non-Hodgkin's) lymphomas, 22 cases of lymphogranulomatosis X and 16 pseudolymphomas were investigated by histology and immunomorphology. Age- and sex-distribution, localization as well as intracytoplasmic immunoglobulins (Ig) in tumour cells were evaluated. Hodgkin's lymphomas were classified according to Lukes (1971), the non-Hodgkin's lymphomas (NHL) according to the Kiel-classification. Among NHL of low grade malignancy the most common type was chronic lymphocytic leukaemia (CLL) (18%), among the NHL of high grade malignancy the immunoblastic lymphomas (IB) (13%). In IB 5 cases of T-cell type of IB were be identified. 8 cases were classified as "histiocytic" reticulosarcomas. Immunomorphology performed on routinely formalin-fixed, paraffin-embedded tissue sections showed a clear-cut difference between CLL and immunocytic lymphomas (IC): In all IC "monoclonal" Ig could be detected in lymphoplasmacytoid and plasma cells. The most common Ig was of the IgM/K type. 4 IC were turned out as "biclonal" ML detected by the double immunofluorescence. In IB lymphomas less than 50% contained intracytoplasmic Ig mainly of the IgM/K type. In Hodgkin's- and Sternberg cells sometimes IgG, K, lambda and also lysozyme was observed intracytoplasmically. This finding supports the hypothesis of the macrophage origin of these cells. In lymphogranulomatosis X and in lymphoepithelioid cell lymphoma (Lennert's lymphoma) as well as in pseudolymphomas "polyclonal" Ig containing "reactive" plasma cells was demonstrable. Immunomorphology on routine pathological material is able to facilitate differential diagnosis of ML and to elucidate to some extent derivation of ML.