Immunohistochemistry in lymphoproliferative diseases.

In diagnostic pathomorphology of lymphoproliferative diseases, immunohistochemical methods are of great importance. These methods help to elucidate the following issues: reactive or malignant nature of a lesion, origin of atypical cells (lymphoreticular or other), type of malignant lymphoma (Hodgkin's disease or malignant non-Hodgkin lymphoma, NHL), grade of malignancy, T- or B-cell origin and subtype of NHLs. All results of immunohistochemistry should be carefully scrutinized in the light of routine pathomorphological findings. The possibilities of immunohistochemistry are demonstrated by two examples: 1. Origin and stage of differentiation of B-cell chronic lymphocytic leukaemia cells with special emphasis on the presence of follicular dendritic reticulum cells in the lymph nodes of a few, otherwise typical cases of CLL. 2. Description of two cases of a new type of NHL that contains intrasinusoidal B-cells. Monoclonal plasma cells with immunoglobulins of the same isotypes as those of intrasinusoidal B-cells were observed in both cases. These findings suggest that the intrasinusoidal B-cells may be plasma cell precursors.