Pathomorphology of hereditary sensory neuropathies

Summary

Currently, the hereditary sensory neuropathies (HSN) — because of the involvement of the autonomic system recently called HSAN — comprise types I–V predicated on clinical differences. This classification of HSAN I–V seems to be uncontested, at the present time. Morphologically, individual forms I–V only differ in the non-specific loss or lack of myelinated and unmyelinated nerves in varying degrees in that in HSAN II large myelinated axons are most affected, in HSAN IV unmyelinated axons are almost absent; but each HSAN is considered an axonal type of neuropathy. Early onset, slow or no progression of the neuropathic process, and little or no evidence of ongoing degeneration suggest maldevelopment of sensory and autonomic components of the peripheral nervous system in certain HSAN. A combined approach by biopsy to peripheral nerves and skin in HSN/HSAN may improve clinico-pathological correlations and is highly recommended to the investigative neuropathologist. Finally, only molecular-genetic data may provide an ultimate nosological classification of the HSN/HSAN.