18F-FDG PET/CT and clinicopathological characteristics of neurolymphomatosis in lymphoma patients.

Objective: Neurolymphomatosis (NL) is a rare but serious manifestation defined as invasion of peripheral nervous system by malignant lymphocytes. Thus, this study investigated fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) and clinicopathological characteristics of NL in lymphoma patients.

Subjects and methods: Clinicopathological and ¹⁸F-FDG PET/CT findings and treatment regimens were retrospectively investigated in 20 lymphoma patients with NL, and analyzed their correlation with progression-free survival (PFS) and overall survival (OS).

Results: These 20 lymphoma patients (11 males, 9 females; median age, 49 years) included 10 primary and 10 secondary NL patients. Non-Hodgkin's lymphoma (NHL) was noted in 19 patients, B-cell NHL was associated with 18 cases, and diffuse large B-cell lymphoma was the most common. Notably, 18 patients were aggressive lymphoma while 2 were indolent lymphoma. The affected neural structures included nerve roots (n=17), peripheral nerves (n=3), cranial nerves (n=3), and neural plexus (n=2). Fluorine-18-FDG was avid in all cases, and the median maximum standardized uptake value (SUVmax) of neural and all lesions was 12.2 (range, 3.3-25.6) and 15.0 (range, 4.4-34.2), respectively. The median PFS and OS of all patients were 9.3 and 14.3 months. The 12-month OS rate of 18 patients with aggressive lymphoma receiving intrathecal chemotherapy/autologous stem cell transplants (IT chem/ASCT) was significantly higher than who did not (64.8% vs 15.9%).

Conclusion: The majority of NL occurred in patients with aggressive lymphoma, of which B-cell NHL were the predominant subtypes. Fluorine-18-FDG PET/CT imaging of NL was mainly characterized by intense glucose accumulation alongside peripheral nerves, and IT chem/ASCT was suggested to improve the outcomes of NL.