STAT6 Immunostain in Solitary Fibrous Tumor
Most solitary fibrous tumors (SFTs) are positive for CD34, bcl2, CD99, and STAT6 (nuclear stain). STAT6 has become valuable in the immunohistochemical diagnosis of SFTs as explained in the previous slide. CD56, and calretinin are sometimes expressed. Desmin, SMA, S100 protein, cytokeratin, and CD117 are generally negative but may be seen in sporadic cases. Malignant SFTs may show aberrant cytokeratin expression and variable (or loss of) CD34 immunoreactivity.