title: Gastrointestinal stromal tumor with skeinoid fibers of the ileum.
abstract: Gastrointestinal stromal tumor (GIST) is not uncommon among gastrointestinal nonepithelial tumors, but there are few reports describing the cytologic findings. We report a case of GIST with skeinoid fibers in scrape cytology preparation. The patient was a 53-year-old man with a tumor in the small intestine. Scrape preparations from the cut surface of the resected tumor revealed cellular material composed of spindle cells showing loose clusters or single cells. The nuclei were spindled, elongated or cigar-shaped, and relatively uniform. The cytoplasm was fragile and demonstrated a finely fibrillar material. Dense hyaline materials with irregular outline were observed within the loose clusters composed of the tumor cells. The hyaline materials were also observed in the background. Histologic preparation showed spindle cells arranged in a fascicular or storiform pattern. Most eosinophilic globules were distributed between the tumor cells. The globules were positive in periodic acid-Schiff reaction, and were stained blue with Masson's trichrome stain. Immunohistochemically, the tumor cells were strongly and diffusely positive for c-kit, focally and weakly positive for alpha-smooth muscle actin, and negative for CD34 and S-100 protein. We emphasize that skeinoid fibers are characteristic of GIST arising in the small intestine, and their presence predicts a good prognosis, even in malignant GIST.
authors.affiliation: Department of Pathology, University of Tokushima School of Medicine, Tokushima, Japan. hirokawa@basic.med.tokushima-u.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Hirokawa
authors.forename: T
authors.initials: T
authors.lastname: Tashiro
authors.forename: H
authors.initials: H
authors.lastname: Horiguchi
authors.forename: S
authors.initials: S
authors.lastname: Wakatsuki
authors.forename: T
authors.initials: T
authors.lastname: Kanahara
authors.forename: Y
authors.initials: Y
authors.lastname: Monobe
authors.forename: T
authors.initials: T
authors.lastname: Sano
mesh_terms: D005770:Gastrointestinal Neoplasms / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007078:Ileal Neoplasms / Q000378:metabolism / Q000473:pathology*; D007082:Ileum / Q000737:chemistry / Q000473:pathology*; D007150:Immunohistochemistry; D008297:Male; D008637:Mesenchymoma / Q000378:metabolism / Q000473:pathology*; D008875:Middle Aged; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis
chemical_list: D019009:Proto-Oncogene Proteins c-kit