Unilateral sporadic retinal dysplasia: results of histopathologic, immunohistochemical, chromosomal, genetic, and VEGF-A analyses

Early Neuroblastic and Astrocytic Differentiation Demonstrated Immunohistochemically in a Small Intraocular Medulloepithelioma

Purpose

To investigate the source of fibrous astrocytes and neuroblasts in a small ciliary body medulloepithelioma appearing as a leukocoria in a 3-week-old baby girl.

Methods

Histopathologic and immunohistochemical studies included Alcian blue, periodic acid-Schiff, and antisera for the detection of S100 protein, CD99, glial fibrillary acidic protein (GFAP), CRX, NeuN, neurofilaments, synaptophysin, desmin, and myogenin.

Results

A small, nonteratoid ciliary body medulloepithelioma with collections of Alcian blue+ mucoplysaccharides was present in the enucleated globe. The retinal mass displayed multilaminar dysplastic rosettes that were CRX+, NeuN-, and synaptophysin-. Intraretinal neurofilaments and scattered NeuN+ neurocytes were also identified. At the base of the retinal mass ribbons and pseudopapillae of CRX+, NeuN- medullary epithelium were found. The latter developed from an S100+ and weakly CD99+ monolayer of premedullary epithelium. GFAP+ fibrous astrocytes and NeuN- neuroblasts streamed from the medullary epithelium.

Conclusions

A multilaminar medullary epithelium and a precursor monolayer of premedullary epithelium were both identified. Neuroblasts and fibrous astrocytes were determined to arise separately from the medullary epithelium. The early stage of tumorigenesis afforded by a small tumor provided the opportunity to discover morphologic and immunohistochemical evidence for these differentiations.

So-called massive retinal gliosis: A critical review and reappraisal

Massive retinal gliosis, a nonneoplastic retinal glial proliferation, was first described in detail over 25 years ago, before the era of immunohistochemistry, in a series of 38 cases-to which can be added 30 case reports or small series (no more than 3 cases) subsequently. We analyze a new series of 3 nontumoral intraretinal glioses and 15 cases of tumoral retinal gliosis, not all of which, strictly speaking, were massive. The data from this series are compared with the findings in previously published cases. Included are 2 cases of massive retinal gliosis diagnosed from evisceration specimens. In reviewing all published and current cases, we were able to establish 3 subgroups of retinal tumoral glioses rather than a single "massive" category: focal nodular gliosis, submassive gliosis, and massive gliosis. Among 43 reported cases, including the present series, but excluding the previous large series of 38 cases in which substantial clinical data were omitted, there were 19 men and 24 women. Their mean and median ages were 36.2 years and 36 years, respectively, with a range of 2 to 79 years. All lesions were composed of mitotically quiet, compact spindled fibrous astrocytes devoid of an Alcian blue-positive myxoid matrix. The most common associated ocular conditions were phthisis bulbi and congenital diseases or malformations. Histopathologically, all 3 tumoral categories were accompanied by progressively more extensive fibrous and osseous metaplasia of the pigment epithelium, the latter forming a clinically and diagnostically useful, almost continuous, outer rim of eggshell calcification in the submassive and massive categories that should be detectable with appropriate imaging studies. In decreasing order of frequency, microcysts and macrocysts, vascular sclerosis, exudates, calcospherites, and Rosenthal fibers were observed among the proliferating fibrous astrocytes. Immunohistochemistry was positive for glial fibrillary acidic protein in all cases and nestin in most (an intermediate cytoplasmic filament typically restricted to embryonic and reparative neural tissue). The nonneoplastic nature of all categories of gliosis was confirmed by absent TP53 (tumor suppressor gene) dysregulation, Ki-67 negativity, and intact p16 expression (the protein product of the p16 tumor suppressor gene) in the overwhelming majority of cases. These findings indicate an intrinsic attempt to regulate and maintain a low level of glial cell proliferation that becomes unsuccessful as the disease evolves. The categories of tumoral proliferation appeared to constitute a spectrum. We conclude that focal nodular tumors encompass lesions previously called retinal vasoproliferative lesions, which display the same histopathologic and immunohistochemical findings as 3 major categories of retinal gliosis characterized herein.

New insights into the development of infantile intraocular medulloepithelioma

PURPOSE

To define the maturational sequence of 3 infantile intraocular medulloepitheliomas.

DESIGN

Retrospective clinicohistopathologic and immunohistochemical study.

METHODS

Immunoreactivity of paraffin sections for CRX (cone-rod homebox transcription factor) and NeuN (biomarker for neuronal differentiation) were investigated together with other biomarkers, including S100, glial fibrillary acidic protein, epithelial membrane antigen, and various cytokeratins.

RESULTS

Three infants (aged 1, 6, and 8 months) had iris neovascularization, 2 had anterior ciliary body tumors, and 1 a posterior tumor associated with a retinochoroidal coloboma. Each tumor displayed a premedullary monolayer of cuboidal epithelium that was S100(+), NeuN(-), and CRX(-) and that transitioned into a multilaminar medullary epithelium forming neurotubules with adluminal cells that were CRX(+). NeuN first appeared in ablumenal neurotubular cells in 1 tumor and was also discovered among neuroblast-appearing cells in another. The third tumor associated with a coloboma was CRX(-) and NeuN(-).

CONCLUSIONS

A simple premedullary epithelial monolayer appears to be the fundamental source for the tumor and its multilaminar medullary epithelium. CRX(+) and NeuN(+) cells within the multilayered medullary layer approximate expression patterns similar to those found in retinal development and differentiation. Discovery of these biomarkers in the neoplastic ciliary epithelium in a small number of tumors indicates preliminarily that the most anterior layers of the optic cup have a retained retinal and neuroglial differentiation potentiality. The third case was CRX(-) and NeuN(-) and possibly arose from embryonic pigment epithelium at the edge of the retinochoroidal coloboma. These immunohistochemical findings offer histogenetic and potential diagnostic insights.