Langerhans cell activation in diabetic small fiber polyneuropathy

A 63-year-old man with type 2 diabetes developed painful feet with touch allodynia. Skin biopsy revealed prominent Langerhans cells (LC) staining with the standard epidermal nerve fiber antibody PGP9.5 when compared to a normal control (figure). Fiber density was severely decreased at the leg (mean 0.2 fibers/mm, 95% confidence interval [CI] 0.1–0.4) and thigh (mean 2.2 fibers/mm, 95% CI 1.8–2.8). These findings were consistent with small fiber neuropathy.