title: Small gastrointestinal stromal tumor in the stomach: identification of precursor for clinical gastrointestinal stromal tumor using c-kit and α-smooth muscle actin expression.
abstract: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the digestive tract. To find precursors for clinical GISTs of the stomach, small gastric stromal tumors of less than 3 cm were collected and examined immunohistochemically with analysis of the KIT mutation. Sixty-eight of 74 lesions were classified into 4 representative groups according to the expression of c-kit and α-smooth muscle actin (αSMA): group A, c-kit diffusely positive and αSMA negative (18 cases); group B, c-kit diffusely positive and αSMA focally positive (13); group C, c-kit focally positive and αSMA diffusely positive (27); and group D, c-kit negative and αSMA diffusely positive (10). Of the 4 groups, groups A and B of c-kit diffuse expression showed higher cellularity and labeling indices of p27(Kip1) and Ki-67 than did groups C and D of diffuse αSMA expression. Incidence of KIT exon 11 mutation in groups A and B was 86% (25/29), whereas that in groups C and D was 0% (0/20). Small gastric stromal tumors with c-kit diffuse expression were considered precursors for clinical GIST because they were significantly different from c-kit focally positive or negative tumors. The mutation of KIT is considered as an early event in tumorigenesis of GIST.
authors.affiliation: Department of Pathology, Toho University School of Medicine, Ota-ku, Tokyo 143-8540, Japan; Department of Pathology, Kitasato University School of Medicine, Sagamihara, Kanagawa 252-0374, Japan. Electronic address: mikamit@med.kitasato-u.ac.jp.
authors.forename: Tetuo
authors.initials: T
authors.lastname: Mikami
authors.forename: Yuta
authors.initials: Y
authors.lastname: Nemoto
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Numata
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Hana
authors.forename: Norihiro
authors.initials: N
authors.lastname: Nakada
authors.forename: Masaaki
authors.initials: M
authors.lastname: Ichinoe
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Murakumo
authors.forename: Isao
authors.initials: I
authors.lastname: Okayasu
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000368:Aged; D000369:Aged, 80 and over; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000473:pathology*; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism; D046152:Gastrointestinal Stromal Tumors / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000378:metabolism / Q000473:pathology; D009154:Mutation; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism*; D013270:Stomach / Q000473:pathology; D013274:Stomach Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D019009:Proto-Oncogene Proteins c-kit
keywords: Gastrointestinal stromal tumor; KIT mutation; Small GIST; Stomach; Tumorigenesis