title: Gastrointestinal stromal tumor and gastric adenocarcinoma collision tumors.
abstract: Gastrointestinal stromal tumors sometimes occur together with gastric carcinoma, but true collision tumors featuring these 2 components are very rare. The authors describe here 2 collision tumors containing a gastrointestinal stromal tumor with intermingling elements of gastric adenocarcinoma. The gastrointestinal stromal tumors were 5.5 to 6 cm spindle cell tumors, and one patient had an additional prepyloric stromal tumor (2.5 cm). All gastrointestinal stromal tumors had low mitotic counts less than 5/50 high-power fields and were positive for KIT, DOG1, and CD34. Different KIT exon 11 mutations (single nucleotide substitution, complex insertion-duplication) in all tumors indicated that the 2 gastrointestinal stromal tumors in one patient were independent primary tumors. The adenocarcinoma components displayed gland-forming intestinal type to signet ring cell morphology with focally accompanying dysplastic epithelium, immunohistochemical positivity for CDX2, and varying keratin 7/20 expression. We hypothesize that development of gastric adenocarcinoma within a gastrointestinal stromal tumor may be based on displaced gastric epithelium in a long-standing stromal tumor with events of intermittent ulceration and epithelial regeneration.
authors.affiliation: Department of Pathology, Soerlandet sykehus HF, Serviceboks 416, N-4604 Kristiansand, Norway. britta.kleist@sshf.no
authors.forename: Britta
authors.initials: B
authors.lastname: Kleist
authors.forename: Jerzy
authors.initials: J
authors.lastname: Lasota
authors.forename: Markku
authors.initials: M
authors.lastname: Miettinen
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology; D000368:Aged; D000369:Aged, 80 and over; D000075369:Anoctamin-1; D018952:Antigens, CD34 / Q000378:metabolism; D018118:Chloride Channels; D017809:Fatal Outcome; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D009154:Mutation; D009363:Neoplasm Proteins / Q000378:metabolism; D009378:Neoplasms, Multiple Primary / Q000378:metabolism / Q000473:pathology; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism; D013274:Stomach Neoplasms / Q000378:metabolism / Q000473:pathology
chemical_list: C476213:ANO1 protein, human; D000075369:Anoctamin-1; D018952:Antigens, CD34; D018118:Chloride Channels; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D019009:Proto-Oncogene Proteins c-kit