[Immunohistochemical localization of S-100 protein in granular cell myoblastoma].

Three cases of granular cell myoblastoma have been studied in order to determine the presence and distribution of the S-100 specific protein in the neoplastic cells, using immunocytochemical staining techniques, through the modified avidin-biotin method. Positive immunostaining was observed in the three cases studied. The comparative study of various control cases histogenetically originating from neuroectoderm (melanoma) and specifically from Schwann cells, as also the presence of strongly positive staining in Schwann cells of peripheral nerve fibres situated inside and outside the tumor, support the concept of the neurogenic origin of this interesting tumor.