Image Description
Histologic Features: Cellular solitary fibrous tumors (hemangiopericytoma pattern) are composed of plump round or oval cells lacking atypia. The cells are arranged haphazardly (patternless pattern) or in short, intersecting fascicles around a network of sinusoidal vessels with staghorn configuration. The cells have moderate amount of eosinophilic cytoplasm with indistinct borders. Mitotic activity is not increased.