Somatomedin C as tentative pathogenic factor in neurofibromatosis

The distribution of somatomedin C (Sm-C; insulin-like growth factor I; IGF-I) immunoreactivity was examined in biopsies from three patients having the diagnosis neurofibromatosis established on clinical and histopathological criteria. All biopsies showed increased Sm-C immunoreactivity limited to areas with neurofibromas. Schwann cells, adjacent spindle-shaped fibroblast-like cells and newly formed blood vessels were positive. In addition, Sm-C immunoreactivity could be demonstrated in cells in the buccal epithelium. There was faint or no Sm-C immunoreactivity in biopsies from normal tissue of the patients and in specimens from control subjects. We propose that an abnormally increased local production of Sm-C, most likely by Schwann cells, forms a link in the chain of pathogenic events resulting in the disease neurofibromatosis.