title: Differential diagnosis of gastrointestinal leiomyoma versus gastrointestinal stromal tumor.
abstract: BACKGROUND
  Strategies for the diagnosis of tumors arising in the intestinal muscular wall are rapidly evolving. Immunoreactivity for CD117 (KIT) usually supports the diagnosis of gastrointestinal stromal tumor (GIST), but a small subset of GISTs lacks KIT expression. In these cases the differential diagnosis of KIT-negative GIST versus one of their morphological mimics is difficult and bears critical implications for therapeutic management.
  
  
  METHODS
  Here, we report a case of a KIT-negative smooth muscle cell tumor of the colon in a 21-year-old man with the clinical appearance of GIST. Mutations of the KIT and platelet-derived growth factor receptor alpha (PDGFRA) gene could be ruled out. No chromosomal imbalances characteristic of GIST were found. However, cytogenetic analysis revealed losses at 7q, which has previously been reported in cases of uterine leiomyoma.
  
  
  CONCLUSIONS
  We discuss current approaches to the differential diagnosis of true gastrointestinal smooth muscle cell tumor versus GIST.
authors.affiliation: Department of General and Visceral Surgery, Albert Schweitzer Hospital, Northeim, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Kuhlgatz
authors.forename: Bjoern
authors.initials: B
authors.lastname: Sander
authors.forename: Mariola Monika
authors.initials: MM
authors.lastname: Golas
authors.forename: Bastian
authors.initials: B
authors.lastname: Gunawan
authors.forename: Thorsten
authors.initials: T
authors.lastname: Schulze
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Schulten
authors.forename: Eva
authors.initials: E
authors.lastname: Wardelmann
authors.forename: László
authors.initials: L
authors.lastname: Füzesi
mesh_terms: D000328:Adult; D001707:Biopsy, Needle; D003082:Colectomy / Q000379:methods; D004252:DNA Mutational Analysis; D003937:Diagnosis, Differential; D046152:Gastrointestinal Stromal Tumors / Q000175:diagnosis* / Q000235:genetics / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D007813:Laparotomy / Q000379:methods; D007889:Leiomyoma / Q000175:diagnosis* / Q000235:genetics / Q000601:surgery; D008297:Male; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics*; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics*; D018570:Risk Assessment; D012811:Sigmoid Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000601:surgery; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D018608:Ultrasonography, Doppler
chemical_list: D019009:Proto-Oncogene Proteins c-kit; D020796:Receptor, Platelet-Derived Growth Factor alpha