[Primary Meningeal Lymphoma Diagnosed Using Cytology and Flow Cytometry-A Case Report]

A 72-year-old male was referred with a 2-week history of diplopia. Following magnetic resonance imaging, an area of abnormal signal intensity was observed along the lateral ventricle, without any unusual findings at other sites. Cerebrospinal fluid cytology revealed abnormal lymphocytes with atypia, which were positive for CD20 and light-chain restriction, as detected by surface marker analysis, leading to a diagnosis of primary meningeal B-cell lymphoma. The patient underwent chemoradiotherapy and achieved a remission. While meningeal lymphoma is a rare occurrence, pathological tissue biopsy is considered the gold-standard diagnostic method. However, obtaining a biopsy sample from the tumor site can be challenging. In this case report, cytology and flow cytometry played a vital role in the diagnosis of meningeal lymphoma.