Gross and microscopic appearances of retinoblastoma are identical in both hereditary and sporadic types.
Macroscopically, viable tumor cells are found near blood vessels, while zones of necrosis are found in relatively avascular areas.
Microscopically, both undifferentiated and differentiated elements may be present.
Undifferentiated elements appear as collections of small, round cells with hyperchromatic nuclei; differentiated elements include Flexner-Wintersteiner rosettes, Homer Wright rosettes,  and fleurettes from photoreceptor differentiation.
Gross and microscopic appearances of retinoblastoma are identical in both hereditary and sporadic types. Macroscopically, viable tumor cells are found near blood vessels, while zones of necrosis are found in relatively avascular areas. Microscopically, both undifferentiated and differentiated elements may be present. Undifferentiated elements appear as collections of small, round cells with hyperchromatic nuclei; differentiated elements include Flexner-Wintersteiner rosettes, Homer Wright rosettes,  and fleurettes from photoreceptor differentiation.
Retinoblastoma