[Pathology and Assessment of Peripheral Autonomic Neuropathy].

The peripheral autonomic nervous system predominantly comprises unmyelinated fibers, which are difficult to evaluate using conventional light microscopy. Historically, morphological assessment of unmyelinated fibers relied on the electron microscopy of sural nerve biopsy specimens, which is a technically demanding approach with limited accessibility to autonomic structures. Skin biopsy with immunohistochemical staining for the pan-axonal marker PGP 9.5 has enabled minimally invasive and quantitative evaluation of somatic small (intraepidermal nerve fiber density) and autonomic fibers innervating sweat glands, arrector pili muscles, and dermal vasculature. An integrated analysis combining autopsy findings, sural nerve biopsy, and skin biopsy may clarify the pathophysiology of peripheral autonomic neuropathy.