Vascular spaces in endolymphatic stromal myosis

Abstract

Endolymphatic stromal myosis usually has extensive vascular invasion and yet has an excellent prognosis. To resolve this paradox, we studied the involved vascular spaces by electron microscopy, immunoperoxidase identification of factor VIII as a marker for endothelium and serial sections for light microscopy. The spaces were shown to be indeed vascular. However, in many spaces the tumor was not present within the lumina. Sheets of tumor cells had indented and invaginated the endothelium creating the illusion that tumor was present within the lumina. The tumor cells were separated from the lumina by intact endothelial cells and basement membrane. The presence of cell junction modifications between endothelial cells and well-developed basement membrane material demonstrated that at least some of the spaces were blood vessels, probably postcapillary venules, and not lymphatics.