RESUMEN
Histochemical and immunohistochemical studies were carried out on 30 biopsy specimens of odontogenic myxoma, myxoid variants of neurofibroma and schwannoma, myxoid liposarcoma and myxoid malignant fibrous histocytoma [MMFH] in an attempt to differentiate between them. Periodic acid-Schiff and alcian blue special stains were used to identify the nature of the extracellular matrix, while the immunohistochemical technique using S-100 protein and vimentin was used to identify the cell of origin in these myoxoid areas. All the studied cases were positive for both alcian blue and PAS except MMFH which was negative for PAS. Considering S-100 protein, it was found to be positive only in neurofibromas and Schwannomas showing myxoid change. In contrast, vimentin was negative in myxoid variants of neurofibroma and Schwannoma as well as myxoid liposarcoma. Vimentin, on the other h and, was strongly positive in myxomas and MMFH indicating a fibroblastic origin. It can thus be concluded that S-100 protein and vimentin are of value in differentiating myxoid variants of neurofibroma and Schwannoma from myxomas and MMFH