PNSL shows persistent severe focal nerve enlargement favoring the initially-affected side and frequent cranial/root involvement, whereas NSVN exhibits mild-to-moderate, variable enlargement with rare cranial/root involvement, so nerve ultrasound may serve as a noninvasive screening tool prior to PET/CT and biopsy.
Cranial nerve involvement was significantly more frequent in PNSL than in NSVN.
Nerve root/plexus involvement was significantly more frequent in PNSL than in NSVN.
Cross-sectional area (CSA) at most median and ulnar nerve sites did not differ significantly between PNSL and NSVN.
PNSL patients had significantly larger CSA of the cervical roots and brachial plexus than NSVN patients, except at the C7 root.
In PNSL, nerve CSA was greater on the initially affected side, whereas in NSVN it was greater on the contralateral side.
The ratio of maximum CSA between bilateral homonymous nerves (onset/contralateral) was significantly higher in PNSL than in NSVN.
The authors conclude that PNSL shows persistent severe focal enlargement and frequent cranial/root involvement, while NSVN shows mild-to-moderate variable enlargement with rare cranial/root involvement.
This small study compared two rare conditions that can look alike: lymphoma that invades the peripheral nerves (PNSL) and vasculitis limited to the nerves (NSVN, inflammation of blood vessels supplying nerves). Researchers looked back at records of 9 patients with PNSL and 7 with NSVN, comparing symptoms, nerve conduction tests, and ultrasound measurements of nerve size. Patients with PNSL much more often had involvement of the cranial nerves (66.7% vs. 0%) and of nerve roots or plexus (88.9% vs. 0%). Ultrasound showed that nerve roots and the brachial plexus in the neck and shoulder region were larger in PNSL. PNSL nerves were also larger on the side where symptoms began, while in NSVN the opposite side was larger. The ratio between the two sides was 1.32 in PNSL versus 0.88 in NSVN. This research suggests nerve ultrasound could help doctors tell these conditions apart without invasive procedures, and could help decide who needs further tests like PET/CT or biopsy. However, the study was very small and retrospective, so the findings need confirmation in larger studies before they can be relied on in practice.
Tian H, Hu N, Ding J, Qian M, Wang Y, Cui L, et al.. (2026). Nerve Ultrasound Features of Peripheral Nervous System Lymphoma and Non-Systemic Vasculitic Neuropathy.. European journal of neurology. https://doi.org/10.1111/ene.70793