A 64-Year-Old Woman with Progressive Pain, Numbness and Weakness in the Right Lower Limb

We describe a case of primary neurolymphomatosis (PNL) with unusual presentation of a right lumbosacral polyradiculoneuropathy with no other lesions shown on the whole body fludeoxyglucose-positron emission tomography (FDG-PET) scan. A right superficial peroneal nerve lesion biopsy revealed infiltration of the nerve by malignant CD20+ lymphoma cells. The lymphoma cells expressed Bcl-2 but not CD10, suggesting an origin in peripheral blood not lymph nodes. The patient responded very well to the combined radiotherapy and chemotherapy with the R-MPV (rituximab, methotrexate, procarbazine, and vincristine) regimen. The patient showed marked clinical improvement and complete resolution of lymphoma lesions on the PET scan.