Willis1 had the opinion that endothelioma cells are merely mesenchymal cells and the specific name is unnecessary, since most of these neoplasms are poorly differentiated sarcomata. Orbital endotheliomata are very rare tumors and are described in textbooks of ophthalmology under 3 main headings: Endotheliomata, Hemangioendotheliomata, and Meningioendotheliomata.
Endotheliomata of the orbit are described as tumors of embryonic endothelial cells of blood vessels. The cells are polyhedral, with faintly staining cytoplasm and vesicular nuclei. Such tumors may occur at any age and affect either sex. They are locally malignant and sometimes give diffuse thickening of the adjacent bone. These tumors were described as endotheliomata by Paton,2 Williamson-Noble,3 Eagleton,4 and others. They were also described by others as angioendotheliomata, endotheliosarcomata and angiosarcomata. According to their cellular arrangement,
MORTADA A. The Histogenesis of Orbital EndotheliomataReport of 2 Cases of Angioendotheliomata and 2 Cases of Meningioendotheliomata. Arch Ophthalmol. 1961;65(5):636-645. doi:10.1001/archopht.1961.01840020638006