title: Alveolar soft part sarcoma of the larynx: a case report of an unusual location with immunohistochemical and ultrastructural analyses.
abstract: BACKGROUND
  Alveolar soft part sarcoma (ASPS) is a rare mesenchymal neoplasm of uncertain origin. In this article, we report a case of ASPS occurring in the larynx, an extremely rare location for this rather unusual tumor.
  
  
  RESULTS
  The patient was a 34-year-old Japanese woman who requested an examination for hoarseness. The tumor showed a proliferation of large polygonal cells with periodic-acid-Schiff-positive diastase-resistant intracytoplasmic granules, arranged in an alveolar growth pattern. The cytoplasm of the tumor cells was eosinophilic. Tumor cells were positive for vimentin and titin. Nuclear immunoreactivity for TFE3 was observed, and the Ki-67 labeling index was 14.7%. Ultrastructurally, electron-dense rod-shaped crystals were infrequently observed in the cytoplasm. This case was finally diagnosed as ASPS of the larynx.
  
  
  CONCLUSIONS
  We discuss the histogenesis and differential diagnosis of ASPS with immunohistochemical and ultrastructural findings. TFE3 immunohistochemistry was found to be a very useful marker for the diagnosis of ASPS.
authors.affiliation: Pathology Division, Shizuoka Cancer Center Hospital and Research Institute, 1007 Shimonagakubo, Nagaizumi-cho, Sunto-gun, Shizuoka 411-8777, Japan. k.kusafuka@scchr.jp
authors.forename: Kimihide
authors.initials: K
authors.lastname: Kusafuka
authors.forename: Koji
authors.initials: K
authors.lastname: Muramatsu
authors.forename: Tsugumi
authors.initials: T
authors.lastname: Yabuzaki
authors.forename: Hiroto
authors.initials: H
authors.lastname: Ishiki
authors.forename: Rie
authors.initials: R
authors.lastname: Asano
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kamijo
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Iida
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Ebihara
authors.forename: Testuro
authors.initials: T
authors.lastname: Onitsuka
authors.forename: Toru
authors.initials: T
authors.lastname: Kameya
mesh_terms: D000328:Adult; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000032:analysis; D001707:Biopsy, Needle; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D007822:Laryngeal Neoplasms / Q000473:pathology* / Q000601:surgery / Q000648:ultrastructure; D007828:Laryngoscopy / Q000379:methods*; D008279:Magnetic Resonance Imaging; D009367:Neoplasm Staging; D035583:Rare Diseases; D018570:Risk Assessment; D018234:Sarcoma, Alveolar Soft Part / Q000473:pathology* / Q000601:surgery / Q000648:ultrastructure; D016896:Treatment Outcome
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C069203:TFE3 protein, human