Weak above the knees: Lumbar Root Non-Hodgkin Lymphoma invasion (P6.126)

Objective: Present a case of Non-Hodgkin lymphoma (NHL) involvement of Lumbar meninges and nerve roots leading to rapidly progressing lower extremity weakness. Background: Central or and peripheral nervous system (PNS) involvement of lymphoma is uncommon, ≤7% of lymphomas. NHL is aggressive; nervous system involvement can occur early, but detection can be challenging. Methods: Case report. Results: A 58-year-old woman with B-cell NHL, diagnosed 5 months prior, on Rituximab monotherapy, presented with lower extremity weakness and four months of worsening lumbago. She initially had right lower extremity (RLE) weakness, progressed to the left, then had mild foot numbness/tingling without saddle anesthesia or incontinence. Her weakness progressed rapidly over a week and she required a cane/crutches. Neurological examination showed intact bilateral upper extremity (BUE) strength, but right/left lower extremity MRC grading revealed hip flexors 0/2, knee extension 0/3+, knee flexion 4−/4+, and foot dorsiflexion 4/5, plantar flexion 5/5. Sensory exam showed decreased sensation in multiple BLE dermatomes. Reflexes were absent in lower extremities; plantars were equivocal. MRI showed cauda equina nerve root thickening with avid enhancement, smooth thickening of multiple peripheral nerve roots and possibly part of the right lumbosacral plexus. Nerve conduction studies demonstrated normal SNAPs. EMG revealed fibrillations and positive sharp waves in L2-5 innervated muscle groups in RLE and paraspinal muscles, along with reduced recruitment, right>left, suggesting axonal lumbosacral polyradiculopathy, worse in right L2–L4 segments. CSF showed protein >600 mg/dL; HIV, Lyme, RPR, HSV, SSA/SSB, ACE (serum/CSF), ANA, CSF oligoclonal bands, and Rheumatoid Factor were negative. CD5+ B-cell Lymphoma in CSF, without residual anti-CD20, confirmed lymphoma invasion. Conclusions: This case establishes the importance of clinical reasoning. Neurological exam suggested multilevel radiculopathy/plexopathy. Normal SNAPS argue against plexopathy, MRI, and CSF analysis confirmed the diagnosis of secondary CNS lymphoma invading the meninges and nerve roots. Disclosure: Dr. Datta has nothing to disclose. Dr. Roy has nothing to disclose. Dr. Meira Benchaya has nothing to disclose. Dr. Boland has nothing to disclose.