title: Rare childhood tumors in a Turkish pediatric oncology center.
abstract: BACKGROUND
  It has been estimated that rare tumor rate is about 15% of all childhood cancer in United States. According to Turkish Pediatric Oncology Group (TPOG) datas, 8889 children were diagnosed between 2002 and 2008 in our country and 3.7% of them were diagnosed as rare tumors.
  
  
  OBJECTIVE
  To investigate the frequency and clinical features of rare tumors in our pediatric oncology center.
  
  
  METHODS
  A total of 43 cases that have diagnosed as rare tumor in 574 cancer patients between the yaer 2002 and 2012 were reviewed retrospectively. All cases definitive diagnosis were established by histopathological and immunohistochemical studies.
  
  
  RESULTS
  Frequency of rare tumors was 7.4% in our center. Benign and border line rare tumors were 27 (62.7%) cases, malignant rare tumor were 16 (37.2%) cases. Median follow-up period was 48 months (between 1 and 110 months). Six of the malignant rare tumors were died with progressive disease (synovial sarcoma, mixed malignant mesenchymal tumor, undifferentiated sarcoma, plexus choroideus carcinoma, renal peripheral primitive neuroectodermal tumor, adrenocortical carcinoma). Malignant rare tumor mortality rate was found 37.5% in our clinic.
  
  
  CONCLUSIONS
  We have found that our rare tumor rate (7.4%) was higher than Turkish rare tumor rate (3.7%) according to TPOG's datas. However, it was still lower than rare tumor rates of western countries (15%), probably due to difficulties of diagnosis and referral problems.
authors.affiliation: Department of Pediatric Oncology, Ankara University, Ankara, Turkey.
authors.forename: Nurdan
authors.initials: N
authors.lastname: Tacyildiz
authors.affiliation: Department of Pediatric Oncology, Ankara University, Ankara, Turkey.
authors.forename: Derya
authors.initials: D
authors.lastname: Ozyörük
authors.affiliation: Department of Pediatric Oncology, Ankara University, Ankara, Turkey.
authors.forename: Gülsan
authors.initials: G
authors.lastname: Yavuz
authors.affiliation: Department of Pediatric Oncology, Ankara University, Ankara, Turkey.
authors.forename: Emel Cabı
authors.initials: EC
authors.lastname: Unal
authors.affiliation: Department of Pediatric Oncology, Ankara University, Ankara, Turkey.
authors.forename: Handan
authors.initials: H
authors.lastname: Dinçaslan
authors.affiliation: Department of Pediatric Oncology, Ankara University, Ankara, Turkey.
authors.forename: Gülşah Oktay
authors.initials: GO
authors.lastname: Tanyıldız
authors.affiliation: Department of Pediatric Oncology, Ankara University, Ankara, Turkey.
authors.forename: Zülfikar
authors.initials: Z
authors.lastname: Gördü
authors.affiliation: Department of Pediatric Endocrinology, Ankara University, Ankara, Turkey.
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Sıklar
authors.affiliation: Department of Pediatric Endocrinology, Ankara University, Ankara, Turkey.
authors.forename: Merih
authors.initials: M
authors.lastname: Berberoğlu
authors.affiliation: Department of Pediatric Endocrinology, Ankara University, Ankara, Turkey.
authors.forename: Gönül
authors.initials: G
authors.lastname: Ocal
keywords: Benign rare tumors; border-line rare tumors; malignant rare tumors