Nerve Ultrasound Features of Peripheral Nervous System Lymphoma and Non-Systemic Vasculitic Neuropathy

To compare the clinical, electrophysiological, and nerve ultrasound characteristics of peripheral nervous system lymphoma (PNSL) and non-systemic vasculitic neuropathy (NSVN).

Between July 2015 and May 2026, 9 PNSL patients and 7 NSVN patients were retrospectively enrolled. Clinical characteristics, electrophysiological studies, and nerve ultrasound data were collected. Cross-sectional area (CSA) was measured at predetermined sites of peripheral nerves.

The PNSL group showed significantly higher rates of cranial nerve involvement (66.7% vs. 0%, p = 0.011) and nerve root/plexus involvement (88.9% vs. 0%, p = 0.001) than the NSVN group. Although CSA at most median and ulnar nerve sites did not differ significantly between groups, the PNSL group showed significantly higher CSA of the cervical roots and brachial plexus than the NSVN group (C5, C6, upper trunk, middle trunk, and lower trunk; p = 0.001-0.018) except C7 root. In the PNSL group, the CSA was significantly greater on the initially affected side than on the contralateral side (p < 0.001), whereas in the NSVN group the CSA was significantly greater on the contralateral side than on the onset side (p = 0.005). The maximum-CSA ratio between bilateral homonymous nerves (affected onset/contralateral) was significantly higher in PNSL than in NSVN (1.32 vs. 0.88, p < 0.001).

PNSL shows persistent severe focal enlargement favoring the initially-affected side and frequent cranial/root involvement, whereas NSVN exhibits mild-to-moderate, variable enlargement with rare cranial/root involvement. Nerve ultrasound may serve as a noninvasive screening tool prior to PET/CT and biopsy.