title: Collision tumor of the stomach: a rare case of an adenocarcinoma and carcinoid tumor.
abstract: We report a rare case of gastric collision tumor composed of moderately differentiated tubular adenocarcinoma and carcinoid in an 84-year-old woman. On endoscopic examination, an invasive tumor was noted at the cardia of the stomach, and a pathologic examination of the biopsy specimen revealed adenocarcinoma. After total gastrectomy, a thorough histopathologic examination of the resected tumor revealed the concurrent presence of moderately differentiated adenocarcinoma and a typical carcinoid tumor, which had a colliding pattern of tissue proliferation. There was no intermixing or transition area between the 2 components. The final pathologic diagnosis was collision tumor of the adenocarcinoma and carcinoid tumor. The presence of either tumor individually would not be especially noteworthy, but this collision-type tumor of both histopathologic types in the stomach is, to our knowledge, only the sixth such case in the literature.
authors.affiliation: Department Pathology, Nihon University School of Medicine, Tokyo, Japan. myukie@med.nihon-u.ac.jp
authors.forename: Yukie
authors.initials: Y
authors.lastname: Morishita
authors.forename: Masahiko
authors.initials: M
authors.lastname: Sugitani
authors.forename: Aleemuzzaman
authors.initials: A
authors.lastname: Sheikh
authors.forename: Norimichi
authors.initials: N
authors.lastname: Nemoto
authors.forename: Masashi
authors.initials: M
authors.lastname: Fujii
authors.forename: Tadatoshi
authors.initials: T
authors.lastname: Takayama
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis*; D000368:Aged; D000369:Aged, 80 and over; D002276:Carcinoid Tumor / Q000175:diagnosis*; D005260:Female; D006801:Humans; D013274:Stomach Neoplasms / Q000175:diagnosis*