title: Leiomyosarcoma with partial rhabdomyoblastic differentiation: first case report of primary cardiac origin.
abstract: BACKGROUND
  Leiomyosarcoma occurring as a primary cardiac tumor has been known as an extremely rare condition. Previous studies of leiomyosarcoma with rhabdomyoblastic differentiation have conducted to those arisen from another site, and they indicated a poorer prognosis of this tumor.
  
  
  METHODS
  A 69-year-old woman was referred to our hospital for an operation concerning umbilical hernia. Subsequent imaging examinations before an operation indicated the presence of primary cardiac malignant tumor due to its atypical shape. And then, it was surgically removed. Histopathologically, tumor cells consisted of two different types: spindle and polyhedral cells. Immunohistochemically, it is interesting to note that 2.1% of spindle cells and 23.1% of polyhedral cells showed positive reactivity for myogenin. Furthermore, we performed double-immunostaining for alpha-smooth muscle actin (SMA) and myogenin. The rates of alpha-SMA and myogenin double negative, alpha-SMA single positive, myogenin single positive, and alpha-SMA and myogenin double positive in spindle cells were estimated as 69.1%, 28.8%, 1.1% and 1.0%, respectively. In contrast, the rates in polyhedral cells were estimated as 76.9%, 0.0%, 23.1%, and 0.0%, respectively.
  
  
  CONCLUSIONS
  Our immunohistochemical evaluation suggested that rhabdomyoblastic differentiation in leiomyosarcoma might be generated not only by de novo generation from mesenchymal cells. To the best of our knowledge, this is the first case of primary cardiac leiomyosarcoma with partial rhabdomyoblastic differentiation.
authors.affiliation: Department of Surgical Pathology, Toho University School of Medicine, 6-11-1 Omori-Nishi, Ota-Ku, Tokyo 143-8541, Japan.
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Okubo
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Shibuya
authors.forename: Atsushi
authors.initials: A
authors.lastname: Namiki
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takamura
authors.forename: Noriaki
authors.initials: N
authors.lastname: Kameda
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nemoto
authors.forename: Aki
authors.initials: A
authors.lastname: Mitsuda
authors.forename: Megumi
authors.initials: M
authors.lastname: Wakayama
authors.forename: Minoru
authors.initials: M
authors.lastname: Shinozaki
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hiruta
authors.forename: Kanako
authors.initials: K
authors.lastname: Kitahara
authors.forename: Takao
authors.initials: T
authors.lastname: Ishiwatari
authors.forename: Junichi
authors.initials: J
authors.lastname: Yamazaki
mesh_terms: D000368:Aged; D002454:Cell Differentiation; D018450:Disease Progression; D005260:Female; D006338:Heart Neoplasms / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D007890:Leiomyosarcoma / Q000175:diagnosis* / Q000473:pathology; D032386:Myoblasts, Cardiac / Q000473:pathology; D012207:Rhabdomyoma / Q000175:diagnosis* / Q000473:pathology