title: A case of low-grade fibromyxoid sarcoma with unusual central necrosis in a 77-year-old man confirmed by FUS-CREB3L2 gene fusion.
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 display fully malignant behavior, and recurrence and metastasis can occur even decades after diagnosis.
  
  
  METHODS
  Herein, we report a case of LGFMS in the buttock of a 77-year-old man. Magnetic resonance imaging uncovered a well-demarcated tumor measuring 27×20mm with a slightly high intensity on T1-weighted images (WIs) and heterogeneously high intensity on T2-WIs. Histologically, the tumor was composed of bland spindle-shaped cells in a whorled growth pattern with alternating fibrous and myxoid stroma. The tumor stroma was variably hyalinized with arcades of curvilinear capillaries and arterioles with associated perivascular fibrosis. Unusual histology, such as central necrosis and cystic formation, was also noted. Reverse transcription polymerase chain reaction from a formalin-fixed, paraffin-embedded biopsy specimen revealed a FUS-CREB3L2 gene fusion (exon6/int/exon5), leading to the diagnosis of LGFMS.
  
  
  CONCLUSIONS
  To the best of our knowledge, this is the second oldest patient to be diagnosed with LGFMS.
  
  
  CONCLUSIONS
  At the time of this report, the patient was alive with no evidence of the disease 4 months after diagnosis without any adjuvant therapy.
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Aiko
authors.initials: A
authors.lastname: Kurisaki-Arakawa
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Akaike
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Ran
authors.initials: R
authors.lastname: Tomomasa
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Arakawa
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Suehara
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Takagi
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kaneko
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yao
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan. Electronic address: tysaitou@juntendo.ac.jp.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Saito
keywords: Elderly patient; FUS-CREB3L2; Fusion gene; Low-grade fibromyxoid sarcoma