A Rare Case of Combined Direct Retinal Involvement and Suspected Bing-Neel Syndrome in a Patient With Waldenstrom's Macroglobulinemia.

A 75-year-old male with a history of Waldenström macroglobulinemia (WM), diagnosed in 2022, presented with several months of progressive blurred vision and floaters in his right eye, impairing his ability to drive, particularly at night. The ophthalmologic evaluation revealed vitreous haemorrhage and sub-retinal pigment epithelial lesions in the superonasal and inferonasal quadrants of the right eye. A pars plana vitrectomy with vitreous biopsy was performed, which was consistent with ocular involvement by WM. The patient underwent orbital radiotherapy. Shortly after completing radiotherapy, he developed acute neurological symptoms, including involuntary movements and erratic behaviour. Based on imaging and clinical presentation, the lesion was highly suspected to represent central nervous system (CNS) involvement by WM (Bing-Neel syndrome), though a tissue diagnosis could not be obtained due to the fitness of the patient. The patient was treated with rituximab and high-dose methotrexate, but after three cycles, follow-up imaging showed progressive CNS disease. Due to his declining condition, any further could not be pursued. At the time of this report, his visual acuity in the right eye was reduced to 6/60 due to silicone oil used during the vitreoretinal surgery, and further review is awaiting. This case illustrates a very rare occurrence of combined direct ocular involvement and suspected CNS infiltration in WM, highlighting the challenges of diagnosing and treating these uncommon but serious manifestations.