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

Background: Recurrences of retinoblastoma tumors, particularly scar recurrences, are a common phenomenon in the management of this cancer. Consolidative treatment with laser and cryotherapy are required for local control of disease. It is known that consolidative therapy can induce retinal pigment epithelium (RPE) hyperplasia and gliosis. Herein we report extensive RPE hyperplasia and gliosis during laser therapy for a focal scar recurrence, which presented as a progressive retinal opacification mimicking active retinoblastoma. Method: This is a retrospective case review. Results: A 2-month-old premature male was diagnosed with sporadic bilateral retinoblastoma (International Intraocular Retinoblastoma Classification [IIRC] group B in the right eye and IIRC group A in the left eye). The patient underwent laser therapy for a focal recurrence which demonstrated a white lesion during therapy and was subsequently enucleated. While there was a focal recurrence and infiltration of the retina (seen both on optical coherence tomography and histopathologic section), the majority of the white, progressive lesion was from extensive RPE hyperplasia and gliosis secondary to laser therapy. Conclusion: Clinicopathologic correlation of the active recurrence and adjacent gliosis is demonstrated.