Diagnosis of central nervous system lymphoma via cerebrospinal fluid cytology: a case report

Primary central nervous system lymphoma (PCNSL) is the most prevalent brain, spinal cord, eyes, and leptomeningeal lymphoma. It is often misdiagnosed due to an unspecific presentation or unavailable biopsy and results in a poor prognosis. Although the craniocerebral imaging examination of PCNSL has some characteristics, it is limited, and atypical cases are especially difficult to identify with intracranial tumours and other diseases. The biopsy, as the gold standard for PCNSL diagnosis, is not eligible for all patients suspected of having PCNSL.

This report documents a woman who presented with a three-month history of numbness and weakness in the right leg. She was treated with drugs at a local hospital for one month. She developed demyelination lesions and her symptoms were aggravated. The patient was admitted to the Department of Nerve Infection and Immunology at Tiantan Hospital. Head magnetic resonance imaging (MRI) enhanced scanning indicated significant inflammatory demyelinating disease, and lymphoma was not excluded. CSF revealed a high protein level and CSF cytology detected abnormal cells, PCNSL was eventually presumed according to positive CSF cytology and cytological detection of the cerebrospinal fluid flow.

PCNSL is a highly invasive tumour. With the development of technologies such as cerebrospinal fluid cytology and flow cytology, CSF analysis has become one of the definite diagnosis methods, and the tumour cell finding in CSF is the only reliable basis for diagnosis. Flow cytometric analysis and gene rearrangement testing also provide objective evidence.