title: Intra-extracranial hemangiopericytoma: clinical manifestations, histopathological features, diagnosis, treatment, and outcomes.
abstract: BACKGROUND
  Intra-extracranial hemangiopericytomas (HPCs) are rare vascular neoplasms. This paper reports the clinical manifestations, histopathological features, diagnosis, treatment, and outcomes of HPCs.
  
  
  METHODS
  We reviewed three patients with intracranial HPC and one patient with HPC of the scalp who were surgically treated at Taichung Veterans General Hospital between 1989 and 1999.
  
  
  RESULTS
  All four patients underwent surgery and postoperative radiotherapy. After surgery, three patients showed improvement compared with their preoperative neurological function. Two patients had recurrent tumors, one patient was well and free from tumor recurrence, and one patient was lost during follow-up.
  
  
  CONCLUSIONS
  Clinical presentation and radiographic appearance of intracranial HPC can be indistinguishable from meningioma. Intracranial HPC is an aggressive neoplasm with malignant potential. Both benign and malignant variations of HPC of the scalp exist. The principal treatment is surgical excision. Survival is influenced by more aggressive primary resection and by postoperative radiotherapy. Recurrences are common. Metastases may be multiple and can develop in many organs and systems.
mesh_terms: D000328:Adult; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000628:therapy; D003131:Combined Modality Therapy; D005260:Female; D006393:Hemangiopericytoma / Q000000981:diagnostic imaging / Q000473:pathology* / Q000628:therapy; D006801:Humans; D008297:Male; D011859:Radiography; D016896:Treatment Outcome