Small-Vessel Vasculitis or Perifolliculitis in Small-Fiber Neuropathy With TS-HDS, FGFR-3, or Plexin D1 Antibodies

Small-fiber neuropathy (SFN) is highly prevalent but often idiopathic. TS-HDS, FGFR-3, and Plexin D1 autoantibodies (seropositive) may be present in more than 40% of idiopathic cases. Another autoimmune biomarker is a non-length-dependent (NLD) skin biopsy pattern. Our goal was to demonstrate that small-vessel vasculitis and perifolliculitis (inflammation) on skin biopsies are additional biomarkers.

All pure SFN skin biopsy reports were reviewed for inflammation, and their charts were examined for other relevant history.

Seven of 80 patients with pure SFN had inflammation (8.8%); 5 patients were female (71%) and 2 were male (29%); average age was 45 (16-67). All 7 patients with inflammation were seropositive (100%, P = 0.0495), and 6 patients (86%) had either NLD inflammation or NLD pathology (P = 0.0003).

Inflammation is present only in a small portion of punch biopsies, but may be another autoimmune SFN biomarker. It is strongly associated with seropositivity and NLD-pathology. Further studies are likely indicated to assess inflammation pathophysiology and immunotherapy responsiveness.