Immunohistochemical diagnosis of a totally necrotic retinoblastoma: a clinicopathologic case

An 8-month-old girl underwent enucleation of her right eye because of a calcified retrolental white mass filling the entire vitreous cavity. The conventional histological examination revealed a totally necrotic unidentifiable tumor, with scattered foci of calcification. In addition, we found two islands of viable small round cells, suspected to be retinoblastoma cells, which were located in the optic nerve behind the lamina cribrosa. These cells stained positively for neuron-specific enolase (NSE), but not for glial-fibrillary-acidic-protein (GFAP), supporting the diagnosis of retinoblastoma. Because one of the latter foci of viable tumor cells was located at the cut end of the optic nerve, the baby was treated by external beam irradiation.