Could Cerebral Inflammatory Lesions be the Cellular Origin of Primary Central Nervous System Lymphoma?

INTRODUCTION: Primary central nervous system lymphoma (PCNSL) presents a diagnostic enigma due to the inherent absence of lymphoid tissue in the central nervous system (CNS). The hypothesis posits that lymphocytes infiltrating the CNS during inflammatory responses could represent a cellular source for PCNSL, challenging traditional understandings of its etiology. PATIENT CONCERNS: In 2 illustrative cases, patients presented with neurological symptoms initially misdiagnosed as encephalitis and demyelinating disease, respectively. These diagnoses were established based on clinical assessments and initial biopsy findings. DIAGNOSIS: Subsequent biopsies, conducted months after the first signs of disease, confirmed the diagnosis of PCNSL in both patients. Identifying CD20-positive tumor cells was pivotal, indicating a B-cell lymphoma origin. INTERVENTIONS: Treatment strategies included high-dose methotrexate chemotherapy for both patients. In addition, the second patient underwent adjuvant whole-brain radiotherapy after the chemotherapy regimen. OUTCOMES: The therapeutic approach significantly reduced tumor size in both cases, with no evidence of recurrence observed during the follow-up period. This outcome underscores the potential efficacy of the chosen interventions. CONCLUSION: In response to inflammatory lesions, lymphocyte infiltration into the CNS may serve as a pivotal origin for tumor cells in PCNSL. These cases highlight the complexity of diagnosing CNS disorders and suggest that various forms of encephalitis in the early stages could influence the prognosis of lymphoma. This insight into the cellular origins and treatment responses of PCNSL contributes to a broader understanding of its pathophysiology and management.