Figure 13b. Unilateral retinoblastoma in 14-month-old boy. (a) Transverse gadolinium-enhanced T1-weighted fat-suppressed MR image (575/15) of eyes. Contrast between tumor and vitreous is diminished because of subretinal blood. Increased SI of the postlaminar optic nerve in continuity with tumor was suspicious for postlaminar tumor invasion (long arrow). Notice shallowness of anterior chamber combined with SI increase of the iris (short arrow). Rubeosis iridis was detected with ophthalmoscopic examination. Shallowness is probably related to presence of neovascular glaucoma combined with elevated intraocular pressure, which is an indication for enucleation without delay. (b) Transverse T2-weighted MR image (2200/120) shows total retinal detachment (black arrow) with subretinal hypointense tumor mass (white arrow). Characteristic blood-fluid level (arrowheads) indicates acute subretinal hemorrhage. (c) Histopathologic specimen shows retinoblastoma (R) with postlaminar optic nerve invasion, detachment of retina (arrowheads), and shallow anterior chamber (AC). Choroid (C) and sclera (S) were not invaded by tumor. (Hematoxylin-eosin stain; original magnification, x3.5 objective.) Optic nerve (O) is also involved. Inset: Detail of optic nerve shows postlaminar tumor invasion (arrows). (Original magnification, x10 objective.)