RESUMEN
Diffuse anterior retinoblastoma is a rare variant of diffuse infiltrating retinoblastoma which occurs in up to 1-2% of cases of retinoblastoma. In diffuse anterior retinoblastoma there is a small focus of tumor in the peripheral retina from which free tumor cells enter the aqueous humor and implant on the ciliary body, iris, lens and trabecular meshwork. Patients most commonly present with pseudouveitis, pseudohypopyon and increased intraocular pressure. The differential diagnosis is broad and all of the reported cases relied upon aspirates from the aqueous humor in order to make the diagnosis prior to proceeding with treatment. Treatment involves enucleation and, depending upon the extent of the tumor, may require systemic chemotherapy or external beam radiation. This review summarizes the 7 previously reported cases of diffuse anterior retinoblastoma, discusses pathologic features, and addresses the challenges of early diagnosis and future directions
RESUMEN
PURPOSE: To investigate the effect of bevacizumab (Avastin; Genentech, San Francisco, CA, USA) on vascular endothelial growth factor (VEGF) expression and inflammation in fibrovascular membranes in patients with proliferative diabetic retinopathy (PDR). MATERIALS AND METHODS: Fibrovascular membranes from 19 eyes of 18 patients with PDR were studied using immunohistochemistry and analyzed in the following 3 groups; group 1: 4 inactive PDR eyes, group 2: 10 active PDR eyes treated preoperatively with adjunctive intravitreal bevacizumab, group 3: five active PDR eyes not treated preoperatively with bevacizumab. Immunohistochemical staining for VEGF, CD31 and CD68 were done. RESULTS: The immunoreactivity to VEGF and CD 31-positive blood vessels was significantly higher in membranes from group 3 than group 1 (p = 0.007 for VEGF, 0.013 for CD 31-positive vessels). Intravitreal bevacizumab caused a reduction in VEGF expression and vascular densities in 4 out of 10 (40%) excised membranes from eyes with PDR. However, six membranes (60%) in group 2 still demonstrated relatively strong VEGF expression and high vascular density. Infiltration of macrophages was observed in 16 out of the 19 membranes, and the density of macrophages was increased in group 2 compared with group 1 (p = 0.043). CONCLUSION: Intravitreal bevacizumab injections caused some reduction in VEGF expression and vascular densities in a limited number of active PDR patients. A single intravitreal bevacizumab injection may not be enough to induce complete blockage of VEGF and pathologic neovascularization in active PDR patients. Repeated injections, panretinal photocoagulation and/or PPV may be necessary following intravitreal bevacizumab to reinforce the anti-VEGF effect of the drug.