Although histologically similar to soft tissue perineurioma, such tumors are composed of two different cytotypes, namely, perineurial cells (EMA/claudin/GLUT1-positive) variably arranged into fascicular, storiform, or reticular arrangements and spindled cells (S100/SOX10-positive) with wavy nuclei, closely reminiscent of schwannian differentiation. This evidence concerns the gene SLC2A1 and perineurioma.