Figure 4a. Retinoblastoma with an infiltrative growth pattern and optic nerve invasion in a 2-year-old adopted Chinese girl whose parents noted squinting of the right eye. Leukocoria was noted by the referring physician. (a) Photograph (H-E stain) of the whole-mount specimen shows diffuse thickening and nodularity of the detached retina (arrowheads) with extension of the tumor into the optic nerve (arrow). (b) Axial thin-section T2-weighted MR image obtained with fat saturation shows the diffusely nodular detached retina, which is hypointense relative to the vitreous. (c) Axial fat-saturated T1-weighted MR image, obtained by using a surface coil after intravenous administration of gadolinium contrast material, shows that the thickened detached retina is hyperintense relative to the vitreous. Invasion of the optic nerve is also evident (arrowhead).