Hemangiopericytoma/Solitary Fibrous Tumor

Hemangiopericytoma (HPC) is a rare type of mesenchymal tumor associated with an aggressive phenotype with a predilection toward poor local control and subsequent metastasis. In place of the hybrid label “solitary fibrous tumor/hemangiopericytoma” used in the 2016 CNS classification, the tumor is now formally referred to as solitary fibrous tumor with a three-tiered CNS grading system. For the purposes of this chapter, the hemangiopericytoma name will be used based on decades of studies utilizing this nomenclature. As these tumors cannot be readily distinguished from other tumorigenic entities by radiographic imaging alone, tissue is required to make an effective diagnosis. The ability to make this diagnosis is vital in the context of HPC as this tumor type requires an aggressive therapeutic approach and vigilant follow-up. The current therapeutic strategy for HPC involves maximal safe surgical resection followed by adjuvant radiotherapy. Repeat resection or salvage radiotherapy is also indicated at the time of recurrence or development of metastasis. By maintaining an attentive follow-up schedule for patients with HPC, clinicians may be able to improve patient outcomes.