Low-Grade B-Cell Neurolymphomatosis: A Case Series and Diagnostic Insight

While peripheral nerve involvement by diffuse large B-cell lymphoma is well-documented, neurolymphomatosis (NL) from low-grade B-cell lymphoma is rare. This study describes the clinical features, diagnostic challenges, and treatment outcomes of patients with low-grade B-cell lymphoma involving peripheral nerves.

We conducted a retrospective review of patients diagnosed with peripheral nerve low-grade B-cell lymphoma at a single institution from January 2009 to July 2024. Data on demographics, imaging, electrodiagnostic studies, biopsy results, and treatment were analyzed. Diagnosis was based on neurological symptoms, nerve biopsy, bone marrow biopsy, and cerebrospinal fluid analysis. Primary outcomes were progression-free survival and overall survival.

Eight patients (median age 67.5 years) were identified. All had lower extremity involvement; 2 also had brachial plexus, 2 had cranial nerve, and one had distal radial nerve involvement. Low-grade NL comprised 14% of all NL cases. Imaging showed a tumefactive pattern in 38% and diffuse involvement in 63%. Electrodiagnostic studies confirmed demyelination and axonopathy. Nerve biopsy confirmed lymphoma in 88%, while bone marrow involvement was seen in 43%. Treatments included rituximab, bendamustine, and methotrexate-based regimens. With a median follow-up of 4.2 years, 40% achieved 5-year progression-free survival and 60% achieved 5-year overall survival. All cases were marginal zone or lymphoplasmacytic lymphoma; one lymphoplasmacytic lymphoma case transformed to diffuse large B-cell lymphoma, resulting in a poorer outcome.

Low-grade B-cell NL remains under-recognized. Nerve biopsy is essential for diagnosis, and early treatment-particularly with rituximab-based therapy-is critical to improve outcomes and prevent transformation to aggressive disease.