Histology
Features of fusiform neoplastic process cells with ovoid or elongated moderately deep-coloured nuclei, leptophyte chromatin, with indistinct cell boundaries and without visible nuclei. No atypia or mitoses were seen. Cells were found in a collagenous substrate arranged in bundles often intertwined with each other and to a lesser extent in small and indistinct swirling formations with relatively sparse allocation of individual feeder cells.
Immunohistochemistry
Several neoplastic cells showed S100 positivity, whereas the opposite neoplastic cells were negative for SMA, Desmin, SOX10, c-kit, CD34, CD99, STAT6 and MUC4. About 2% of the nuclei of neoplastic cells show positivity for the mitotic marker Ki-67.
