title: Clinicopathological features of primary leiomyosarcoma of the gastrointestinal tract following recognition of gastrointestinal stromal tumours.
abstract: OBJECTIVE
  We aimed to elucidate the clinicopathological and immunohistochemical features of leiomyosarcoma (LMS) of the gastrointestinal (GI) tract.
  
  
  RESULTS
  We encountered seven cases of GI-LMS in the colon (n = 4), rectum (n = 1), jejunum (n = 1) and stomach (n = 1). They ranged from 1 to 25 cm (median, 8.5 cm) in size and had high mitotic counts (median 38 per 50 high-power fields). Morphologically, the tumours were composed mainly of spindle cells with eosinophilic cytoplasm and various degrees of nuclear atypia and pleomorphism. Immunohistochemically, the tumours were positive for α-smooth muscle actin (86%), muscle-specific actin (71%), desmin (86%), calponin (71%), h-caldesmon (57%) and smoothelin (71%). All were negative for KIT, CD34, protein kinase C theta and DOG1. Local recurrence and distant metastasis occurred in one and three patients, respectively. We then reviewed 55 cases of GI-LMS from the era following the recognition of gastrointestinal stromal tumours. Among 29 of 55 cases for whom follow-up information was available, the estimated 5-year overall survival rate was 51.6%; tumour size ≥5 cm was correlated significantly with shorter overall survival time (P = 0.0016), while mitotic count (≥50 or ≥100 per 50 high-power fields) proved to be no prognostic factor.
  
  
  CONCLUSIONS
  GI-LMSs have distinctive clinicopathological and immunohistochemical features and exhibit aggressive biological behaviour.
authors.affiliation: Department of Anatomic Pathology, Kyushu University, Fukuoka, Japan. hidetaka@surgpath.med.kyushu-u.ac.jp
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Mizuki
authors.initials: M
authors.lastname: Handa
authors.forename: Taro
authors.initials: T
authors.lastname: Tobo
authors.forename: Nokitaka
authors.initials: N
authors.lastname: Setsu
authors.forename: Kohei
authors.initials: K
authors.lastname: Fujita
authors.forename: Yumi
authors.initials: Y
authors.lastname: Oshiro
authors.forename: Yumi
authors.initials: Y
authors.lastname: Mihara
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Yoshikawa
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Oda
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D046152:Gastrointestinal Stromal Tumors / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D007890:Leiomyosarcoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009124:Muscle Proteins / Q000378:metabolism; D009154:Mutation; D011379:Prognosis; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics
chemical_list: D009124:Muscle Proteins; D019009:Proto-Oncogene Proteins c-kit; D020796:Receptor, Platelet-Derived Growth Factor alpha
keywords: GIST; gastrointestinal; immunohistochemistry; leiomyosarcoma; prognosis