Atypical Retinal Pigment Epithelial Hyperplasia and Glial Proliferation Masquerading as Progressive Recurrent Retinoblastoma: A Case Report Review and Clinicopathologic Correlation

Retinal pigment epithelium exhibits gene expression and phagocytic activity alterations when exposed to retinoblastoma chemotherapeutics

Retinoblastoma (Rb) is a rare malignant disorder affecting the developing retina of children under the age of five. Chemotherapeutic agents used for treating Rb have been associated with defects of the retinal pigment epithelium (RPE), such as hyperplasia, gliosis, and mottling. Herein, we have developed two pluripotent stem cell (PSC)-RPE models to assess the cytotoxicity of known Rb chemotherapeutics such as Melphalan, Topotecan and TW-37. Our findings demonstrate that these drugs alter the RPE by decreasing the monolayer barrier's trans-epithelial resistance and affecting the cells' phagocytic activity. Transcriptional analyses demonstrate an altered expression of genes involved in melanin and retinol processing, tight junction and apical-basal polarity pathways in both models. When applied within the clinical range, none of the drug treatments caused significant cytotoxic effects, changes to the apical-basal polarity, tight junction network or cell cycle. Together, our results demonstrate that although the most commonly used Rb chemotherapeutic drugs do not cause cytotoxicity in RPE, their application in vitro leads to compromised phagocytosis and strength of the barrier function, in addition to changes in gene expression that could alter the visual cycle in vivo. Our data demonstrate that widely used Rb chemotherapeutic drugs can have a deleterious impact on RPE cells and thus great care has to be exercised with regard to their delivery so the adjacent healthy RPE is not damaged during the course of tumor eradication.

[Evaluation of the effectiveness of organ preservation treatment of choroidal melanomas by optical coherence tomography findings]

Achieving local tumor control is generally considered to be the criterion of effectiveness of organ preservation treatment. In most cases it can be assessed by ophthalmoscopy and ultrasonography. However, in presence of pigmentation areas, it can be difficult to interpret the ophthalmoscopy and ultrasonography findings. The works concerning the informativity of optical coherence tomography (OCT) after organ preservation treatment of choroidal melanomas (CM) generally cover the complications (post-radiation maculopathy, neuropathy) and the identification of vitreomacular tractions. In evaluation of local control, attention is paid to the presence of subretinal fluid and/or retinal pigment epithelium (RPE) detachment.

PURPOSE

To analyze OCT findings in terms of the condition of eye fundus tissues in various outcomes of organ preservation treatment of CM.

MATERIAL AND METHODS

The study included 20 patients (20 eyes) who underwent the following organ preservation therapy 1 to 374 months prior to enrollment: transpupillary thermotherapy (TTT) - 8 eyes, brachytherapy (BT) - 8 eyes, BT with subsequent TTT - 4 eyes. Mean age of patients at the time of therapy start was 59.25±10.86 (33-81) years. In multi-step therapy (12 eyes), the mean interval between the stages was 28.08±20.39 months. According to echobiometry findings, tumor prominence at the time of therapy start was 3.35±2.08 (1-7.37) mm. At the time of post-treatment OCT scan, there was no prominence in 5 eyes, in other eyes it was 1.26±1.24 (0.4-5.7) mm.

RESULTS

Comparison of ophthalmoscopy picture with OCT findings allowed identification of the following changes: a scar and hyperplasia of pigment epithelium in the scar, a scar with reactive pigment hyperplasia at the level of RPE and choroid, radioreaction, growth area from under and inside the scar, incomplete local control, absence of local control.

CONCLUSION

The author's own expertise in evaluating the effectiveness of local choroidal melanoma therapy suggests that optical coherence tomography should be used to monitor all patients being followed up after organ preservation treatment of choroidal melanoma: after transpupillary thermotherapy - for 3 months, after brachytherapy - during first 24 months, and in case of doubts for longer.

Progressive Preretinal Fibrosis with Late, Ossifying, Proliferative Retinopathy following Treatment for Retinoblastoma

We report a case of retinal atrophy and progressive preretinal fibrosis in an eye previously treated with intravenous and intra-arterial chemotherapy (IAC), which evolved immediately after treatment with intravitreal injection of melphalan. The atrophy and fibrosis progressed later to proliferative retinopathy with dystrophic ossification. The patient was originally diagnosed with bilateral retinoblastoma at 4 months of age and was treated with systemic chemotherapy followed by IAC. New vitreous seeds developed and required treatment with intravitreal chemotherapy. There was resolution of vitreous seeding after 2 doses of intravitreal melphalan, but clinically the eye developed new, widespread retinal atrophy and fibrosis within 1 month of the second injection. This was followed by phthisis and late proliferative retinopathy nearly 1 year later. Retinoblastoma specialists should be aware of this potential complication of combined chemotherapy treatments.