Objective:

N/A

Background:

Accurate diagnosis of Central nervous system (CNS) lymphoma, a rare and aggressive subtype of non-Hodgkin lymphoma, is essential for effective treatment planning and can be achieved by tissue biopsy or cytopathologic analysis of cerebrospinal fluid (CSF). We report a case of a 30-year-old man with recurrent CNS lymphoma in which CSF flow cytometry via lumbar puncture yielded persistently negative results while the presence of B-cell lymphoma was found when CSF was sampled from the lateral ventricle.

Design/Methods:

A case report

Results:

Case Presentation: The patient was initially diagnosed with Diffuse Large B-cell Lymphoma with non-germinal center phenotype, CD20+/CD5+/BCL2(weak)/BCL6+, and an atypical T-cell population, concerning for concurrent T-cell lymphoma with cytotoxic phenotype, involving the small intestine causing perforation. He underwent treatment with R-CHOP/R-EPOCH with complete systemic response. Ten months later the patient presented with cognitive decline. MRI of the brain and spine showed diffuse subependymal and leptomeningeal enhancement in the lateral, third, and fourth ventricles, brainstem, and upper cervical cord with focal C3-7 myelitis. Systemic imaging was negative for lymphoma. A total of 13 lumbar punctures over three months yielded CSF with atypical T-cells though no detectable malignant lymphoid cells by flow cytometry or cytology. Biopsy of an involved area of the meninges showed fibrosis without evidence of neoplastic, granulomatous, or infectious processes. CSF flow cytometry from the ventricle promptly demonstrated the presence of B-cell lymphoma cells. This diagnostic challenge prompted further treatment.

Conclusions:

The incongruent CSF flow cytometry results from lumbar puncture and ventricular sampling underscores the importance of considering alternative sampling sites, such as cisternal or ventricular, when faced with persistently negative CSF results from a lumbar puncture, where there remains clinical concern for CNS lymphoma.