A young boy presented with a history of leukocoria and esotropia in the right eye. Examination revealed unilateral International Classification of Retinoblastoma group E retinoblastoma in the right eye. After discussion of treatment options with the family, enucleation was performed. Histopathologic examination confirmed the diagnosis and ruled out optic nerve or choroidal invasion. This case demonstrates the 2 principal growth patterns of retinoblastoma—exophytic and endophytic—in the same eye. The exophytic pattern, in which the intraretinal tumor grows in the direction of the subretinal space, is exemplified by the large bilobed subretinal mass. The endophytic pattern, in which the tumor grows in the direction of the vitreous cavity and invades the inner retinal layers, is evidenced by several fluffy preretinal tumors with seeding into the vitreous (Figure).1-3 Understanding these growth patterns is key to differentiating retinoblastoma from other simulating lesions in young children.
Paez-Escamilla M, Bagheri N, Harbour JW. Retinoblastoma With Endophytic and Exophytic Features. JAMA Ophthalmol. 2018;136(1):e175064. doi:10.1001/jamaophthalmol.2017.5064
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