Primary Neurolymphomatosis: A Literature Review.

backgroundPrimary neurolymphomatosis (PNL) is a rare clinical entity resulting from direct lymphomatous infiltration into the peripheral nervous system. Its diagnosis is challenging as the hematological condition is unknown at the onset of neurological symptoms.

methodsWe report two of our own cases and the first extensive review of published cases of PNL to delineate its clinical features, paraclinical investigation results, progression, and treatment response more precisely. We extracted demographic data, clinical presentation, results of the investigations performed, type and number of treatments, overall survival, and progression-free survival.

resultsWe describe 301 cases of PNL in patients with a mean age of 57.9 years, 61% of whom were men. The most common clinical presentation was an often painless asymmetric neuropathy. Other presentations included multifocal neuropathy preferentially affecting the sciatic and peroneal nerves, radiculopathy, brachial plexus lesions, cauda equina syndrome, and cranial nerve palsy. Systemic signs and deterioration of clinical status were uncommon. Diagnosis was established after a median of 8 months, based on histological results (76%) or a cluster of elements in cases of positive PET findings. A B-cell lymphoma was diagnosed in 73% of cases. Systemic chemotherapy (90%) and rituximab (60%) were the most common treatments, with a response rate of 45%. Relapse occurred in 24% of patients, and 55% ultimately died from PNL. Overall survival was 28 months. Type of treatment was not associated with survival.

conclusionsThis literature review provides an overview of the available data concerning PNL presentation and progression.