Increased cystatin C immunoreactivity in the skin in amyotrophic lateral sclerosis

Objectives - Several abnormalities of skin have been described in patients with amyotrophic lateral sclerosis (ALS). Bunina bodies, which are small eosinophilic intraneuronal inclusions in the remaining lower motor neurons in ALS, are the only pathologically specific hallmark of ALS. It has been demonstrated that Bunina bodies were positive for anti-cystatin C serum. However, cystatin C in the skin of ALS has not been investigated. Material and methods - We studied cystatin C immunoreactivity of skin in ALS patients, and the results were compared with those of control subjects. Results - The epidermis of ALS was immunohistochemically strongly positive for cystatin C as compared with that of controls. The optical density of cystatin C immunostaining reactivity in ALS patients was significantly higher than in controls, and was significantly increased with duration of illness. Conclusion - These data suggest that a metabolic alteration of cystatin C may take place in the skin of ALS and the increased cystatin C in skin is likely to be related to the disease process in ALS.