Fig. 4.

Histology and immunohistochemistry of the malignant solitary fibrous tumor (SFT). Atypical spindle cells proliferated in the major hypercellular area (a). The tumor showed typical SFT-like features with ovoid nuclei and a thick collagenous stroma (b). Tumor cells demonstrated immunoreactivity for STAT6, a hallmark of SFT (c). The tumor expressed IGF2. Characteristic dot-like reactivity corresponding to the Golgi complex was apparent (d). The tumor also showed immunoreactivity for IGF2R (e)