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M. Evans, T. Albini, N.A. Rao; Immunohistochemical analysis of glial cells in retinoblastoma . Invest. Ophthalmol. Vis. Sci. 2004;45(13):3548.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Molecular studies of retinoblastoma cultures have shown that neoplastic cells arise from photoreceptors. However, histopathologic examinations have previously revealed both photoreceptor and glial elements that were considered by some neoplastic, and by others reactive. To address the neoplastic vs reactive features of the glial cells we compared the distribution of glial cells in tumor localized to the retina to their distribution at the site of choroidal invasion. Methods: We evaluated 38 enucleated eyes harboring retinoblastoma, with or without massive choroidal invasion. Histologic sections were prepared for staining with GFAP, CD34 and CLA and for dual staining with CD34 and GFAP after antigen retrieval. The stains were evaluated for distribution of glial cells, presence of leucocytes, and their relation to CD34–positive vascular channels. Results: Twenty–six of the 38 eyes showed tumor without choroidal invasion, 4 with focal choroidal invasion (less than 1DD), and 8 with extensive choroidal invasion (more than 1DD). Thirty–six eyes revealed the presence of GFAP–positive cells in a perivascular distribution in the tumor. These glial cell elements were predominantly found near the optic nerve head and their number was markedly reduced in the tumor away from the disc. Cases with vitreous seeding or with tumor cells in the anterior chamber and trabecular meshwork rarely demonstrated glial cells at these sites. In 11 cases with choroidal invasion, at the invasion site GFAP–positive cells were absent. There was no difference in the number or distribution of glial cells in tumors displaying Flexner–Wintersteiner rosettes vs. undifferentiated features. However, areas with fleurette differentiation showed numerous GFAP–positive cells. Moreover, there was no difference in number of CD34 + vessels in those tumors localized to the retina vs tumors with choroidal invasion. There were few CLA–positive cells in the retinal component of the tumor and in the choroidal invasion. Conclusions: The absence of glial cells within the choroidal invasion suggests that retinoblastoma is a neuronal tumor without glial cell differentiation and that the glial cells noted in the tumor may represent a reactive process. Moreover, the tumor induces a mild inflammatory response.
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