Ultrastructural localization of S-100 protein in neurofibroma

Abstract

The nature of the cells in neurofibromas was studied by electron microscopy and immunoelectron-microscopic examination of S-100 protein. Ultrastructurally, all five neurofibromas studied were found to be composed of Schwann cells, perineurial cells, and intermediate cells, which had features of both perineurial cells and fibroblasts. The Schwann cells had complex, branched cytoplasmic processes and a continuous basal lamina. The perineurial cells were distinguishable from Schwann cells by the presence of numerous pinocytotic vesicles, unbranched slender cytoplasmic processes and a discontinuous basal lamina. The intermediate cells had no basal lamina, but were topographically related to Schwann cells and had a similar fine structure to that of perineurial cells. Thus, they seemed to be modified neoplastic perineurial cells. Immunoelectron-microscopic studies showed the presence of cells with and without S-100 protein in the neurofibromas: cells with S-100 protein resembled Schwann cells ultrastructurally, and those without S-100 protein were perineurial and intermediate cells. Some Schwann cells with S-100 protein in one neurofibroma had numerous pinocytotic vesicles characteristic of perineurial cells, suggesting that Schwann cells and perineurial cells are functional variants of the same cell type. Thus this study showed that neurofibromas were composed of Schwann cells with S-100 protein and perineurial and intermediate cells, including so-called endoneurial fibroblasts, without S-100 protein. Morphological and functional transition seems to occur between Schwann cells and perineurial cells, and between perineurial cells and intermediate cells.

Immunohistochemical Demonstration of EMA/Glut1-Positive Perineurial Cells and CD34-Positive Fibroblastic Cells in Peripheral Nerve Sheath Tumors

“…Our immunohistochemical results may also suggest the presence of intermediate The constituents of neurofibromas are still controversial (9). Ultrastructural studies suggested the presence of perineurial cells, endoneurial fibroblasts, and intermediate cells, as well as Schwann cells (5,8). However, the heterogeneous cell populations have not been confirmed immunohistochemically (9,16,17).…”

“…Furthermore, there were a few cells exhibiting both perineurial (Glut1) and fibroblastic (CD34) immunophenotypes at the peripheral areas close to the capsule. Some ultrastructural studies of neurofibromas indicated the presence of an intermediate type of cells, between perineurial cells and fibroblasts (5,8). Our immunohistochemical results may also suggest the presence of intermediate The constituents of neurofibromas are still controversial (9).…”

“…Perineuriomas are composed of EMApositive cells, which also possess ultrastructural characteristics of perineurial cells (7). On the other hand, although ultrastructural studies have demonstrated the presence of Schwann cells, perineurial cells, and fibroblastic cells (5,8), the participation of perineurial cells in neurofibromas has not fully been proven immunohistochemically (9). The constituents of malignant peripheral nerve sheath tumors (MPNST) are still poorly understood.…”

Endolaryngeal Excision of Recurrent Laryngeal Nerve Neurofibroma

“…Neuro fibromas consist of Schwann cells with S100 protein and also contain cells without S100 protein, namely perineu rial, intermediate cells and endoneurial fibroblasts. 16 CD 34 positive stromal cells are typically seen in neuro fibromas. 17,18 Calretinin was cited as an aid to distin guish schwannomas from neurofibromas by Fine et al 19 Calretinin is strongly expressed by schwannomas.…”

MicroRNA Inhibitors as Anticancer Therapies

“…Recurrence is associated with increased morbidity and fatality, with progression to malignancy occurring in about 6% of NF1 patients. Although neurofibromas show marked cellular heterogeneity, Schwann cells (SCs) are the major cell type amplified and typically comprise 40-80% of the tumor cells (Hirose et al, 1986;Krone et al, 1986). Moreover, cumulative evidence indicates that neurofibromas contain a clonal population of Schwann cells that have disruptive mutations on the remaining NF1 allele .…”