Neurologic Clinical, Electrophysiologic, and Pathologic Characteristics of Primary vs Secondary Neurolymphomatosis.

in Neurology by Michael P Skolka, Narupat Suanprasert, Jennifer M Martinez-Thompson, Rebecca L King, William R Macon, Michelle L Mauermann, Christopher J Klein, Thomas M Habermann, Patrick B Johnston, Ivana N Micallef, Arushi Khurana, Kimberly Amrami, Robert J Spinner, Jay Mandrekar, Peter J Dyck, P James B Dyck

TLDR

  • The study looked at two types of neurolymphomatosis (NL), primary NL (PNL) and secondary NL (SNL). The study found that PNL patients took longer to be diagnosed than SNL patients, and their symptoms were similar. The study also found that SNL patients had more mononeuropathies (a type of nerve damage) than PNL patients. The study used different imaging techniques to look at the nerves and found that MRI was better at detecting NL than fluorodeoxyglucose (FDG)-PET CT imaging. The study also looked at the tissue samples from the nerves and found that both groups had similar types of nerve damage, but SNL had more axonal degeneration (a type of nerve damage) and multifocal myelinated fiber loss (a type of nerve damage). The study also found that identifying SNL resulted in treatment modifications but a worse prognosis compared with PNL.

Abstract

Neurolymphomatosis (NL) is characterized by lymphomatous infiltration of the peripheral nervous system presenting as the initial manifestation of a lymphoma (primary NL [PNL]) or in relapse of a known lymphoma (secondary NL [SNL]). This report details and compares the neurologic clinicopathologic characteristics of these 2 groups. This retrospective study was performed on patients diagnosed with pathologically confirmed NL in nerve between January 1, 1992, and June 31, 2020. Patient clinical characteristics, neurologic examination, imaging studies, EMG, and nerve biopsy data were collected, analyzed, and compared between PNL and SNL. A total of 58 patients were identified (34 PNL and 24 SNL). Time from neurologic symptom onset to diagnosis was longer in PNL at 18.5 months compared with 5.5 months in SNL (= 0.01). Neurologic symptoms were similar in both patient groups and included primarily sensory loss (98%), severe pain (76%), and asymmetric weakness (76%). A wide spectrum of EMG-confirmed different neuropathy patterns were observed, but patients with SNL had increased numbers of mononeuropathies (n = 8) compared with PNL (n = 1,= 0.01). MRI studies detected NL more frequently (86%) compared with fluorodeoxyglucose (FDG)-PET CT imaging studies (60%) (= 0.007). Nerve biopsies revealed B-cell lymphoma (PNL n = 32, SNL n = 22), followed by T-cell lymphoma (PNL n = 2, SNL n = 2), with increased demyelination in both groups and increased axonal degeneration (= 0.01) and multifocal myelinated fiber loss (= 0.04) significant in SNL vs PNL. Identifying SNL resulted in patient treatment modifications but a worse prognosis compared with PNL (= 0.025). While PNL and SNL are both primarily painful and asymmetric neuropathies with axonal and demyelinating features on EMG and nerve biopsy, SNL presents somewhat differently than PNL with fulminant, asymmetric often mononeuropathies better detected on MRI than FDG-PET/CT. The focal pattern of SNL is likely a result of residual cancer cells that evaded initial chemotherapy, which does not cross the blood-nerve barrier, and these cells can later recur and result in fulminant disease. Although still resulting in a poorer prognosis, identifying SNL is important because this changed treatment and management in every SNL case.

Overview

  • The study focuses on comparing the neurologic clinicopathologic characteristics of primary neurolymphomatosis (PNL) and secondary neurolymphomatosis (SNL).
  • The methodology used for the experiment includes a retrospective study on patients diagnosed with pathologically confirmed NL between January 1, 1992, and June 31, 2020. Patient clinical characteristics, neurologic examination, imaging studies, EMG, and nerve biopsy data were collected and analyzed. A total of 58 patients were identified, with 34 in the PNL group and 24 in the SNL group. The primary objective of the study is to compare the neurologic clinicopathologic characteristics of PNL and SNL.

Comparative Analysis & Findings

  • The study found that the time from neurologic symptom onset to diagnosis was longer in PNL compared with SNL. Neurologic symptoms were similar in both patient groups, primarily sensory loss, severe pain, and asymmetric weakness. A wide spectrum of EMG-confirmed different neuropathy patterns were observed, but patients with SNL had increased numbers of mononeuropathies compared with PNL. MRI studies detected NL more frequently compared with fluorodeoxyglucose (FDG)-PET CT imaging studies. Nerve biopsies revealed B-cell lymphoma in both groups, followed by T-cell lymphoma, with increased demyelination in both groups and increased axonal degeneration and multifocal myelinated fiber loss significant in SNL vs PNL. Identifying SNL resulted in patient treatment modifications but a worse prognosis compared with PNL.

Implications and Future Directions

  • The study's findings suggest that SNL presents somewhat differently than PNL, with fulminant, asymmetric often mononeuropathies better detected on MRI than FDG-PET/CT. The focal pattern of SNL is likely a result of residual cancer cells that evaded initial chemotherapy, which does not cross the blood-nerve barrier, and these cells can later recur and result in fulminant disease. The study highlights the importance of identifying SNL, as this changed treatment and management in every SNL case. Future research could focus on developing more sensitive and specific imaging techniques for detecting SNL and improving treatment outcomes for this group of patients.
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