title: Gastrointestinal stromal tumor in ascitic fluid. A case report.
abstract: BACKGROUND
  There are few published data on the cytologic features of gastrointestinal stromal tumors (GISTs) in ascitic fluid and whether these features may mimic those of other malignancies.
  
  
  METHODS
  An 80-year-old woman presented with ascitics associated with multiple intraperitoneal masses. Cytologic examination of the ascitic fluid showed numerous three-dimensional clusters of epithelioid cells. These features and the presence of large, intracytoplasmic vacuoles raised a possible diagnosis of adenocarcinoma. However, mucin could not be demonstrated in the vacuoles, and the cells showed immunoreactivity for vimentin and c-kit but not for cytokeratins. Eighteen months earlier the patient had undergone a partial gastrectomy for a GIST, which predominantly comprised vacuolated, epithelioid cells. The immunoprofile of the primary tumor was identical to that of the ascitic fluid cells.
  
  
  CONCLUSIONS
  GIST cells may closely mimic adenocarcinoma cells in ascitic fluid. Distinguishing between the two neoplasms has important clinical repercussions and is aided by histochemical and immunocytochemical studies--in particular, c-kit immunostaining.
authors.affiliation: Department of Pathology, University of Edinburgh Medical School, Department of Surgery, Royal Infirmary of Edinburgh, Edinburgh, U.K. nacs.wong@ed.ac.uk
authors.forename: Newton A C S
authors.initials: NA
authors.lastname: Wong
authors.forename: Mark R
authors.initials: MR
authors.lastname: Broadbent
authors.forename: Simon
authors.initials: S
authors.lastname: Paterson-Brown
authors.forename: Awatif
authors.initials: A
authors.lastname: al-Nafussi
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D000368:Aged; D000369:Aged, 80 and over; D001202:Ascitic Fluid / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000473:pathology*; D006801:Humans; D007633:Keratins / Q000032:analysis / Q000276:immunology; D009077:Mucins / Q000032:analysis / Q000276:immunology; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis / Q000276:immunology; D017154:Stromal Cells / Q000473:pathology*; D014617:Vacuoles / Q000737:chemistry; D014746:Vimentin / Q000032:analysis / Q000276:immunology
chemical_list: D009077:Mucins; D014746:Vimentin; D007633:Keratins; D019009:Proto-Oncogene Proteins c-kit