Bone and soft tissue Case 10. Lower leg mass (2.5 cm) from a young patient.

From figure 1, we can see that the tumor is well-circumscribed and encapsulated. Figure 2, 3, and 4 show that the tumor cells are epithelioid, with myxoid and collagenous stroma. The tumor cells are mitotically active and with nuclear atypia (nuclear size variation > 3 :1). The tumor cells are diffusely positive for S100, SOX10, and show nuclear loss of INI1 stain.