Unveiling the Hidden Threat: Late-Onset Retinoblastoma Mimicking Pars Planitis

To report the case of late-onset retinoblastoma (Rb) in a 13-year-old male masquerading as pars planitis.

Case report.

The patient presented with an 8-month history of progressive visual loss in his right eye and a nonremarkable history of blunt trauma. He had been diagnosed with the impression of pars planitis versus organized vitreous hemorrhage in another center and was referred to us 6 months later. Fundus examination with indirect ophthalmoscopy at our center revealed a fundus mass with diffuse vitreous seeding. Hence, the diagnosis of late-onset Rb was made, and complete regression of the tumor was achieved using intra-arterial and intravitreal chemotherapy.

In conclusion, Rb as a "masquerading syndrome" should be considered in the differential diagnosis of patients with atypical presentation of inflammatory diseases. Although these cases usually result in enucleation, with the help of new targeted treatment modalities, favorable outcome might be achievable despite the initial delay in diagnosis.