title: Deeply located low-grade fibromyxoid sarcoma with FUS-CREB3L2 gene fusion in a 5-year-old boy with review of literature.
abstract: BACKGROUND
  Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue tumor typically affecting young to middle-aged adults. Despite its otherwise benign histologic appearance and indolent nature, it can have fully malignant behavior, and recurrence and metastasis may occur even decades later.
  
  
  METHODS
  We report a case of LGFMS in the left lower leg of a 5-year-old Japanese boy. A magnetic resonance imaging (MRI) uncovered a well-demarcated intra-gastrocnemial tumor measuring 27 × 20 mm with a slightly high intensity on T1WI and heterogeneously high intensity on T2WI. Histologically, the tumor was composed of bland spindle-shaped cells with a whorled growth pattern. The tumor stroma was variably hyalinized and fibromyxoid with arcades of curvilinear capillaries and arterioles with associated perivascular fibrosis. Although LGFMS is known to affect children under 18 years of age, it is extremely rare in infants and children under 5 years of age. Despite the young age, this patient was accurately diagnosed by the typical histology and the detection of a FUS-CREB3L2 gene fusion.
  
  
  CONCLUSIONS
  Although LGFMS in children tends to be located superficially, this case presented with an intramuscular tumor in the region of the gastrocnemius. To the best of our knowledge, this is the first case of deep LGFMS arising in a child younger than 5 years of age. The patient is still alive with no evidence of the disease 4 months after diagnosis.
  The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_163.
authors.forename: Aiko
authors.initials: A
authors.lastname: Kurisaki-Arakawa
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Suehara
authors.forename: Atsushi
authors.initials: A
authors.lastname: Arakawa
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Takagi
authors.forename: Michiko
authors.initials: M
authors.lastname: Takahashi
authors.forename: Keiko
authors.initials: K
authors.lastname: Mitani
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kaneko
authors.forename: Takashi
authors.initials: T
authors.lastname: Yao
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan. tysaitou@juntendo.ac.jp.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Saito
mesh_terms: D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics*; D002675:Child, Preschool; D005354:Fibrosarcoma / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D015514:Oncogene Proteins, Fusion; D034702:RNA-Binding Protein FUS / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012983:Soft Tissue Neoplasms / Q000473:pathology*
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; C518609:CREB3L2 protein, human; D015514:Oncogene Proteins, Fusion; D034702:RNA-Binding Protein FUS