Small fiber neuropathy in sclerodermic patients

Scleroderma is a chronic inflammatory disease of the connective tissue. Peripheral nerve involvement is considered rare in scleroderma. Functional and morphological peripheral nerve anomalies have been described in a subpopulation of sclerodermic patients by several authors. We performed skin biopsies using 3-mm disposable punches to study the skin innervation in affected and unaffected cutaneous areas from five patients with circumscribed scleroderma compared to normal subjects. Once fixed and cryoprotected, the skin specimens were cut in 100-pm-thick sections and immunostained, using primary antibodies specific for collagen (Col IV), nerve fibers (POP 9.5) and myelin sheet (MBP), linked to secondary antibodies labeled with Cy3 and Cy5 fluorophores. Digitized, completely in focus 3D images were obtained from z-series of 2-um thick optical sections acquired with a confocal microscope (LSM 410 Invert, Zeiss). In sclerodermic patients, both in the affected and unaffected skin, there was a marked loss of nerve fibers: epidermal nerve fibers were reduced and subepidermal neural plexus appeared poor as well as the innervation of blood vessels and sweat glands. In some areas along the basement membrane dermis and epidermis appeared separated. Punch skin biopsy showed to be an appropriate tool to investigate the neuropathy in sclerodermic patients. Studying the nerve extreme terminations this technique can unveil very mild neuropathies otherwise unidentifiable.