Retinoblastoma: clinical and immunocytochemical observations.

The clinical features of three cases of retinoblastoma and the histopathological and immunocytochemical findings of the retinoblastoma specimens of these patients are described. The other eye of each patient was normal. There was no family history of retinoblastoma. Fundal examination disclosed white masses in the posterior segments of the eyes. B-scan ultrasonography showed echo dense areas in the masses. Orbital tomograms showed no evidence of tissue densities. There was neither extraocular extension nor optic nerve involvement. Immunocytochemistry of paraffin-embedded tissues of the neoplasms revealed immunoreactivity with antibodies against S-100 protein, glial fibrillary acidic protein(GFAP), vimentin, neuron-specific enolase(NSE) and bcl-2. S-100, GFAP and vimentin were positive only for glial elements(reactive astrocytes) and, NSE and bcl-2 for almost all tumor cells. These findings support the previous reports that the majority of retinoblastomas are sporadic. The results of this study also support the views that retinoblastomas are composed of neuron-committed cells.