Malignant lymphoma in pleural effusions: an immunocytochemical cell surface analysis.

Nine malignant pleural effusions due to lymphoma were immunocytochemically analyzed with the peroxidase-antiperoxidase adhesive slide assay for detection of cell surface antigens using a broad panel of monoclonal antibodies. The study population included one case of hairy-cell leukemia; four cases of B cell non-Hodgkin's lymphoma (B-NHL), low malignant grade; two cases of B-NHL, high malignant grade; one case of Hodgkin's disease; and one case of plasmacytoma. In the cases of B cell lymphoma, high percentages of B cells with monoclonal staining for kappa were found. In hairy-cell leukemia, the hairy cells reacted with the monoclonal antibodies CD20, CD25, HLA-DR, CD45, and HLA-1. In Hodgkin's disease, the Hodgkin cells reacted with CD15, CD20, CD25, CD30, Tü9, and OKT9. The plasmacytoma case showed tumor cells negative for CD20, HLA-DR, and CD45; partially positive for CD38; positive for HLA-1; monoclonally positive for lambda; and negative for heavy-chain immunoglobulins. The analysis of nonmalignant lymphocyte subpopulations revealed CD4/CD8 ratios similar to those in effusions of other etiologies. The percentages of natural killer cells (Leu-7-positive and CD16-positive) were small and also similar to percentages in effusions of other etiologies. We conclude that immunocytochemical analysis of pleural effusions allows a clear recognition of B lymphoma cells and also of Hodgkin and hairy cells and that the distribution of nonmalignant lymphocyte subsets is indistinguishable from those found in other malignant and nonmalignant effusions.