Case of Primary Leptomeningeal Lymphoma Presenting with Papilloedema and Characteristics of Pseudotumor Syndrome.

The authors describe an immunocompetent, 50-year-old man who complained of a daily transient blurring of his vision with bilateral papilloedema. His visual acuity was 20/20 OU, and the blind spot was enlarged bilaterally. There was intracranial hypertension, but imaging for systemic and brain tumours were negative. These findings suggested a diagnosis of the pseudotumor syndrome. However, MRI showed leptomeningeal enhancement, and acetazolamide successfully resolved his visual symptoms and papilloedema. Cytology and flow cytometry of the CSF led to the final diagnosis of primary leptomeningeal lymphoma (PLML). Clinicians need to be aware that a case of PLML may be misdiagnosed as peudotumor cerebri.