Fibrosarcomatous foci of de-differentiation, which usually constitute up to 5–10% of the entire tumor, are characterized by “herringbone”—rather than storiform—or fasciculated architecture, being composed of spindle cells with moderate to focally severe nuclear atypia; mitotic activity is increased while immunoreactivity for CD34 is usually reduced when compared to the surrounding typical dermatofibrosarcoma areas. Here, CD34 is linked to dermatofibrosarcoma protuberans.