An immunohistochemical study on "neoplastic angioendotheliosis": demonstration of B lymphocyte markers in the neoplastic cells.

Frozen cerebral and renal tissue sections of an autopsied "neoplastic angioendotheliosis (NAE)" case were investigated immunohistochemically using monoclonal and heterologous antibodies to lymphocyte, monocyte, endothelial, epithelial and histiocytic antigens. In both tissues, positive stainings for surface immunoglobulin (sIg) mu and chi, but not lambda, were observed in most of the neoplastic cells. These cells were also positive for other B cell markers (BA-1, Leu-12 and HLA-DR). No distinct staining was observed in the neoplastic cells with antibodies to T lymphocyte (OKT-11 and Leu-1) or monocyte (OKM-1) markers. Positive stainings were observed only in some small round lymphoid cells which were distributed sporadically in and around blood vessels and were considered to be reactive. No positive staining was observed in the neoplastic cells with antibodies to endothelial (factor VIII), epithelial (cytokeratin) or histiocytic (lysozyme) antigens. Thus, our NAE case was shown to be of monoclonal B cell lymphoma in nature.