Expression of lymphocyte-associated antigens on neoplastic angioendotheliomatosis

Neoplastic angioendotheliomatosis (NAE) is a rare and fatal disorder and has been regarded as a multifocal in situ neoplastic change of endothelial cells. This report describes a case of NAE from whom a biopsy specimen was obtained and studied immunohistologically using several monoclonal antibodies against lymphocyte-associated antigens. The tumor cells occluding luminal space express both T and B cell markers such as Leu-1, Leu-3, Leu-10, Leu-M3, HLA-DR, and HLA-DQ, whereas they do not express Leu-2, Leu-4, lymphocyte-common antigen, and immunoglobulins. Factor VIII as a marker of vascular endothelial cell is false positive in the present case. Since immunoglobulins as a definitive B lymphocyte marker are negative in this case, there is no direct evidence indicating that NAE is a tumor of B lymphocytic lineage as previously reported. These results suggest the two possibilities that NAE is a unique variant of T cell lymphoma or true vascular endothelial tumor sharing the common histogenesis with malignant lymphoma. As it stands the former possibility is more likely than the latter in our case.