Retinoblastomas are rapidly growing malignant tumors of the retina. They arise from the nuclear layers of the retina and are, therefore, neuroectodermal in character. The characteristic growth pattern of the retinoblastomas is that the neuroectodermal tumor cells arrange themselves in lobules around many newly formed vascular channels. These arise from the retinal blood vessels and represent the blood supply of the tumor. In most cases the growth of the fibrovascular stroma of the retinoblastomas cannot keep up with the rapid growth of the tumor cells. Thus, the tumors often "outgrow their own blood supply" despite continuous neovascularization. As a result areas of necrosis and secondary calcification are typically found in the spaces between the lobules of tumor cells arranged around the blood vessels. This is especially common in the most rapidly growing nondifferentiated retinoblastomas without rosettes.
A new technique recently introduced by Kuwabara and Cogan1 makes it possible for
WOLTER JR. The Blood Vessels of Retinoblastomas. Arch Ophthalmol. 1961;66(4):545-551. doi:10.1001/archopht.1961.00960010547018