Secondary Versus Recurrent Central Nervous System Lymphoma: Evaluating the Similarities and Differences in a...

Primary central nervous system lymphoma (PCNSL) is a rare malignancy that affects only a small number of individuals. A subset of these cases may later relapse as recurrent central nervous system lymphoma (RPCNSL), while systemic lymphomas may progress to secondary central nervous system lymphoma (SCNSL). Although these entities differ in origin, they often present with overlapping clinical and radiologic features, complicating diagnosis and management.

This study aims to compare the clinical presentations, treatment histories, lesion characteristics, and outcomes of patients with RPCNSL and SCNSL in a single-institution cohort in an attempt to identify key distinguishing features and shared patterns. Improved understanding of these similarities and differences may enhance diagnostic accuracy, guide treatment strategies, and inform surveillance approaches.

We conducted a retrospective chart review of six patients (three with RPCNSL, three with SCNSL) treated at our institution between 2010 and 2020. Demographic data, initial cancer diagnosis and treatment, central nervous system (CNS) involvement, imaging findings, clinical symptoms, and outcomes were analyzed.

All RPCNSL lesions were solitary and localized to the frontal or temporal lobes, while SCNSL lesions were multifocal in two of three patients. Altered mental status was a common presenting symptom across both groups. Treatment regimens and timing of CNS involvement varied widely. All RPCNSL patients eventually transitioned to hospice care.

Despite differing pathogeneses, SCNSL and RPCNSL share overlapping clinical features that may obscure timely diagnosis. Recognizing their distinct patterns in lesion distribution, timing of CNS involvement, and treatment history is crucial for tailoring care and improving outcomes. Larger studies are needed to validate these findings and support the development of evidence-based guidelines.