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Washington University Experience | NEOPLASMS (MESENCHYMAL, NON-MENINGOTHELIAL) | Solitary Fibrous Tumor (SFT) | 14B1 Hemangiopericytoma, anaplastic (Case 14) H&E 2

14B1,2 This is a highly cellular tumor with rich vascularity. The neoplastic cells have scant amount of eosinophilic cytoplasm and contain round to oval nuclei with coarsely clumped chromatin. Mitoses are frequent, focally reaching ~9/10HPF. Several geographic areas of necrosis are present; some of which may be secondary to pre-surgical embolization of the tumor. In some areas, the tumor has a characteristic staghorn vascular pattern. A reticulin stain not only highlights the vasculature but also shows patchy areas of rich reticulin mesh-work around individual tumor cells.

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