Primary Central Nervous System Lymphoma as a Masquerade of Uveitis: A Case Report of Ocular Involvement

Primary central nervous system lymphoma (PCNSL) often presents with ocular involvement that mimics benign inflammatory conditions, frequently delaying diagnosis. We report a case of a 41-year-old healthy woman presenting with diminished vision and floaters. Examination revealed panuveitis with characteristic hypopigmented retinal lesions exhibiting a 'leopard-skin' pattern. Despite the absence of systemic symptoms and a vitreous sample of low cellularity, diagnostic pars plana vitrectomy confirmed large B-cell lymphoma via immunophenotyping (CD20, CD79a and PAX5). Subsequent magnetic resonance imaging (MRI) demonstrated a parieto-occipital brain mass. The patient received high-dose methotrexate-based chemotherapy according to the DeAngelis protocol, combined with rituximab, selected to optimise disease control while minimising the neurotoxicity associated with whole-brain radiotherapy. She achieved visual recovery to 6/9 and regression of the central nervous system (CNS) lesion. This case underscores the importance of recognising pathognomonic retinal signs and employing molecular immunophenotyping to enable timely, life-saving, neuro-sparing therapy.