title: Secondary resistance of extra-gastrointestinal stromal tumors to imatinib mesylate: report of a case.
abstract: Extra-gastrointestinal stromal tumors (EGISTs) that do not originate in the digestive tract are rare. We report a case of multiple EGISTs, which was monitored closely by KIT gene mutation analysis and other investigations. The patient was a 52-year-old man in whom multiple tumors in the abdominal cavity were diagnosed as EGISTs. Immunohistochemical analysis revealed positive staining for c-kit; however, no mutations were found in the KIT gene. The tumors decreased in size remarkably following treatment with imatinib mesylate, but after 2 years of this treatment, multiple liver metastases and some regrowth of the abdominal masses were found simultaneously. The liver metastasis and the abdominal masses were excised, and further analysis of the KIT gene revealed the same mutation in exon 11 in the KIT gene in the metastatic tumors. We speculate that the treatment might have triggered development of the imatinib mesylate-resistant clone, which may have existed in the primary lesion as a KIT gene mutant. This report provides valuable insight into the mechanisms of recurrent GISTs after treatment with imatinib mesylate.
authors.affiliation: Department of Surgery and Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Ando
authors.forename: Eiji
authors.initials: E
authors.lastname: Oki
authors.forename: Masahiko
authors.initials: M
authors.lastname: Sugiyama
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhao
authors.forename: Aya
authors.initials: A
authors.lastname: Kojima
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Saeki
authors.forename: Akinobu
authors.initials: A
authors.lastname: Taketomi
authors.forename: Masaru
authors.initials: M
authors.lastname: Morita
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kakeji
authors.forename: Shunichi
authors.initials: S
authors.lastname: Tsujitani
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Maehara
mesh_terms: D000008:Abdominal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001549:Benzamides; D019008:Drug Resistance, Neoplasm; D006801:Humans; D000068877:Imatinib Mesylate; D008113:Liver Neoplasms / Q000235:genetics / Q000556:secondary; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000235:genetics; D009372:Neoplasms, Connective Tissue / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D009378:Neoplasms, Multiple Primary / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D010879:Piperazines / Q000627:therapeutic use*; D011743:Pyrimidines / Q000627:therapeutic use*
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate