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M. E. Orellana, E. Antecka, S. C. Maloney, J. Bush, D. Abdulmannan, M. N. Burnier, Jr.; Immunohistochemical Analysis of Retinoblastoma Cell Phenotype Using Neural and Glial Cell Markers. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1691.
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© ARVO (1962-2015); The Authors (2016-present)
Retinoblastoma is the most common intraocular tumor in childhood yet its origin remains unclear. It has been shown that retinoblastoma cells express both mature and immature retinal markers. An immunohistochemical analysis of the cell origin of this particular tumor may yield valuable insight into disease progression. This study aims to determine the origin of retinoblastoma in a large case series and correlates these findings with histopathological prognostic factors.
Twenty retinoblastoma cases were histopathologically diagnosed and further analyzed by immunohistochemistry using monoclonal antibodies against the immature retinal stem cell marker, SOX-2 (SRY-box containing gene 2), the mature retinal stem cell marker, MAP2 (microtubule-associated protein 2), and a glial cell marker, GFAP (glial fibrillary acidic protein). Histopathological features, including pattern of growth, differentiation, vitreous seeding, choroidal, optic nerve, and anterior chamber invasion, were evaluated.
Cytoplasmic expression of SOX-2 was strong in 19 of 20 (95%) of retinoblastoma cells, while MAP-2 was weakly expressed in 15 of 20 (75%) cases. These results were statistically significant (Fisher Exact Test, p < 0.0001). Immunostaining for GFAP was consistent across all twenty cases; positive exclusively in reactive stromal astrocytes interspersed amongst tumor cells. There was no correlation between histopathological prognostic factors and the immunohistochemical markers we evaluated.
These results suggest that the majority of retinoblastomas expressed immature rather than mature retinal cell markers. Therefore, these results indicate a neural origin of this particular tumor. In addition, the absence of GFAP positivity in tumor cells further suggests a retinal cell origin of retinoblastoma. These results may provide fundamental information for the development of tumor-specific therapies.
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