Fig. 1

Histological features of conventional and dedifferentiated solitary fibrous tumors. a Solitary fibrous tumor composed of a fascicular or haphazard proliferation of spindle to oval cells with bland oval to spindle nuclei, pale eosinophilic cytoplasm. and abundant collagenous stroma. b A tumor composed of a solid proliferation of round to epithelioid cells with increased cellularity and less collagenous stroma. c So-called hemangiopericytoma-like vasculature. d Dedifferentiated areas showing a high-grade sarcoma component composed of anaplastic cells with severe nuclear atypia