[Granular cell tumor and congenital epulis. Histochemical and immunohistochemical of 58 cases]

56 cases of granular cell tumour and 2 cases of granular cell congenital epulis have been studied morphologically, histochemically and immunohistochemically. The subject of this study is to evaluate the diagnosis interest of the PAS stain, determine the positivity of 4 antibodies (vimentin, NSE, PS100, NK1/C3) and confirm or not the neuroectodermic origin. The study showed that the microscopic findings are often sufficient. When the diagnosis is less evident, the PAS stain is not discriminant, but we can use the immunohistochemistry study: we confirmed the positivity of the 4 antibodies, but PS100 and NK1/C3 are the most constant. Only the 2 cases of granular cell congenital epulis always show negative immunoreactivity with S100 protein. About the histogenesis, our study confirm the neurogenic origin, but the hypothesis of a non neoplastic nature is raised.