Peripheral neuropathy in systemic sclerosis with proximal nerve involvement: Diagnostic challenges and response to corticosteroid therapy.

Peripheral neuropathy is a complication in systemic sclerosis (SSc) that is occasionally encountered in clinical settings. The mechanisms underlying this condition remain unclear and treatment strategies have not yet been established, making management challenging. Here, we report a case of peripheral neuropathy associated with SSc that was successfully treated with corticosteroid therapy despite the absence of conventional inflammatory findings on histopathology or blood tests. A 44-year-old Japanese man diagnosed with SSc presented with gradually worsening paresthesia and gait disorder. A nerve conduction study and histological examination of a biopsy sample from the left sural nerve, where the nerve conduction study indicated abnormalities, revealed findings consistent with peripheral neuropathy associated with SSc. The results of blood tests or cerebrospinal fluid analysis did not indicate significant inflammatory findings, aside from a slight elevation in protein levels in the cerebrospinal fluid. Similarly, the histological analysis of the nerve biopsy showed no signs of inflammation. T2-weighted magnetic resonance imaging of the lumbar region revealed hyperintensity at the nerve roots, suggesting inflammation at the nerve roots. Based on these findings, we initiated corticosteroid therapy, which led to an improvement in both the patient's symptoms and results in the nerve conduction study. This case provides new insights into the pathogenesis of peripheral neuropathy associated with SSc and highlights that the potential benefits of immunosuppressive therapy should not be overlooked, even in the absence of conventional inflammatory signs.