CD34 is a sialylated transmembrane
glycoprotein of unknown function that is present in myeloid progenitor cells, endothelial cells, and some fibroblast-related mesenchymal cells. However, its tissue distribution is still incompletely characterized. In this study we evaluated the distribution of
CD34 antigen in
tumors of the central and peripheral nervous system. For comparison the
tumors were also stained for CD31, also known as platelet-endothelium
cell adhesion molecule (PECAM-1), a transmembrane
glycoprotein so far considered to be endothelium specific beyond its reactivity with certain hematopoietic cells.
Neurofibromas showed consistently high numbers of CD34-positive spindle cells, whereas peripheral and
acoustic schwannomas were negative. A subset of
meningiomas (15%) showed CD34-positive
tumor cells, and some were also weakly positive for CD31.
Gliomas were negative. Meningeal
hemangiopericytomas were consistently CD34 positive, but CD31 negative. These results indicate a moderately widespread distribution of the
CD34 antigen in
nervous system tumors, and necessitate caution in making conclusions regarding endothelial cell differentiation of
nervous system tumors on the basis of CD34 immunoreactivity.