Introduction Causes of small‐fiber peripheral neuropathies (SFN) are often undefined. In this study we investigated associations of serum autoantibodies, immunoglobulin G (IgG) vs fibroblast growth factor receptor‐3 (FGFR‐3), and immunoglobulin M (IgM) vs trisulfated heparan disaccharide (TS‐HDS) in cryptogenic SFN. Methods One hundred fifty‐five patients with biopsy‐proven SFN and no identified cause for their neuropathy were blindly tested for serum IgM vs TS‐HDS and IgG vs FGFR‐3. Results Forty‐eight percent of SFN patients had serum antibodies, 37% with IgM vs TS‐HDS and 15% with IgG vs FGFR‐3. TS‐HDS antibodies were more frequent in SFN patients than in controls (P = .0012). Both antibodies were more common in females, and with non–length‐dependent nerve pathology. Nintey‐two percent of patients with acute‐onset SFN had serum IgM vs TS‐HDS. Discussion Autoantibodies directed against TS‐HDS and FGFR‐3 suggest an immune disorder in otherwise idiopathic SFN. Serum IgM vs TS‐HDS may be a marker for SFN with an acute onset.

The mean volumetric growth rate was significantly greater than the planimetric growth rate, suggesting that volumetric measurement conveys more information and is superior in assessing tumor growth. This information could have clinical value in determining the frequency of follow-up imaging and the urgency of surgical intervention.

Objective:Novel antibodies to trisulfated heparin disaccharide (TS-HDS) and fibroblast growth factor receptor 3 (FGFR-3) have been recently described in otherwise cryptogenic small fiber neuropathy (SFN) cases. Our goal was to further describe clinical features in such cases and to analyze treatment responses.