Intraocular dissemination or de novo disease? Distinguishing primary vitreoretinal lymphoma from secondary lymphoma

This report describes a rare case most consistent with presumed primary vitreoretinal lymphoma (PVRL) in a patient with a remote history of follicular B-cell lymphoma, highlighting the clinical, imaging, and systemic features that help distinguish PVRL from secondary intraocular lymphoma. A 62-year-old male in long-term remission presented with decreased vision in the left eye. Fundus examination revealed an irregular yellow-white subretinal lesion with characteristic leopard-spot pigmentation. Optical coherence tomography demonstrated multiple hyperreflective nodular deposits at the level of the retinal pigment epithelium (RPE) and sub-RPE space, with associated RPE disruption and scattered vitreous hyperreflective foci. Systemic and central nervous system involvement were excluded on positron emission tomography. The absence of systemic disease, combined with vitreoretinal and sub-RPE infiltration, favored a diagnosis of de novo PVRL. In contrast, secondary intraocular lymphoma typically presents with predominant choroidal involvement, often as smooth, homogeneous choroidal infiltrates with minimal vitreous participation. This case underscores the importance of integrating multimodal imaging and systemic evaluation to accurately differentiate primary from secondary intraocular lymphoma, particularly in patients with a prior history of systemic lymphoma.