title: Childhood hemangiopericytoma: review of St Jude Children's Research Hospital.
abstract: BACKGROUND
  Hemangiopericytoma (HPC) is a heterogeneous, highly vascularized malignant soft-tissue neoplasm with 2 different clinical presentations: adult-type and infantile-type HPC. Intracranial HPC represents a special subtype with a high proclivity toward recurrence and metastasis.
  
  
  METHODS
  The authors have reviewed the clinical features, response to treatment, and outcomes of 17 patients with HPC treated at St Jude Children's Research Hospital from 1962 to 2009.
  
  
  RESULTS
  At diagnosis, 11 patients were older than 1 year (subgroup A) and 6 patients were younger than 1 year (subgroup B). Subgroup A: median age at diagnosis 13.5 years, (range, 4 to 20 y). Primary sites were intracranial (n=5), thigh (n=3), calf (n=1), foot (n=1), and scalp (n=1). One patient who presented with a thigh HPC had metastatic disease at diagnosis, and 3 patients with head location had unresectable tumors. Two patients with thigh location experienced objective responses to chemotherapy. Six patients died of disease progression, 4 of them had an intracranial location. The remaining 5 children are alive at follow-up of 12 to 32 years. Subgroup B: median age at diagnosis 0.5 months (range, 0 to 3 mo). Primary sites were thigh (n=2), calf (n=1), perianal (n=1), forearm (n=1), and lung (n=1). Three patients with limb location had unresectable disease at diagnosis, 2 of them experienced excellent responses to neoadjuvant chemotherapy and 1 did not show any response to chemotherapy and a staged resection was performed. All 6 infants are alive without evidence of disease at follow-up of 2 to 27 years.
  
  
  CONCLUSIONS
  Infantile HPC is characterized by a better clinical behavior than the adult type, which requires an aggressive multimodality therapy. Chemoresponsiveness and spontaneous regression have been reported in children younger than 1 year, suggesting that a more conservative surgical approach should be used. Intracranial HPC is considered as an aggressive tumor because of its propensity for recurrence and metastasis.
authors: Department of Surgery, St Jude Children's Research Hospital, Memphis, TN 38105-3678, USA. israel.fernandez@stjude.org
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