title: Perivascular epithelioid cell tumor of the descending colon mimicking a gastrointestinal stromal tumor: a case report.
abstract: BACKGROUND
  We present a case of perivascular epithelioid cell tumor (PEComa), which clinically and histologically mimics a gastrointestinal stromal tumor (GIST).
  
  
  METHODS
  A 42-year-old woman was found to have a mass in the left flank during her annual medical checkup. Computed tomography examination revealed a submucosal tumor of the descending colon. Surgeons and radiologists suspected that the lesion was a GIST, and left hemicolectomy was performed without biopsy. Microscopic examination showed that the lesion was composed of spindle and epithelioid cells, which were immunohistochemically negative for c-kit and positive for platelet-derived growth factor receptor (PDGFR) α. Initial diagnosis of PDGFRα-positive GIST was made. However, gene analysis did not reveal mutations in PDGFRα. Additional immunohistochemistry showed that tumor cells were positive for human melanin black 45 (HMB45), melanA, and the myogenic marker calponin. A final diagnosis of PEComa was made.
  
  
  CONCLUSIONS
  PEComa should be included in the differential diagnosis of PDGFRα-positive spindle cell tumors in the wall of the gastrointestinal tract.
authors.affiliation: Department of Diagnostic Pathology, Kyoto University Hospital, 54 Syogoinkawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.|Department of Pathology, Japan Red Cross Society Wakayama Medical Center, 4-20 Komatsubara-dori, Wakayama, 640-8558, Japan.
authors.forename: Ryuta
authors.initials: R
authors.lastname: Iwamoto
authors.affiliation: Department of Diagnostic Pathology, Kyoto University Hospital, 54 Syogoinkawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan. trkataoka@yahoo.co.jp.
authors.forename: Tatsuki R
authors.initials: TR
authors.lastname: Kataoka
authors.affiliation: Department of Diagnostic Pathology, Kyoto University Hospital, 54 Syogoinkawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Furuhata
authors.affiliation: Department of Pathology, Japan Red Cross Society Wakayama Medical Center, 4-20 Komatsubara-dori, Wakayama, 640-8558, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Ono
authors.affiliation: Department of Surgical Pathology, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo, 663-8501, Japan.
authors.forename: Seiichi
authors.initials: S
authors.lastname: Hirota
authors.affiliation: Department of Surgery, Kyoto University Hospital, 54 Syogoinkawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kawada
authors.affiliation: Department of Surgery, Kyoto University Hospital, 54 Syogoinkawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Sakai
authors.affiliation: Department of Diagnostic Pathology, Kyoto University Hospital, 54 Syogoinkawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Hironori
authors.initials: H
authors.lastname: Haga
mesh_terms: D000328:Adult; D001706:Biopsy; D002135:Calcium-Binding Proteins / Q000378:metabolism; D003082:Colectomy; D044683:Colon, Descending / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D003110:Colonic Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D003937:Diagnosis, Differential; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000000981:diagnostic imaging / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D058965:MART-1 Antigen / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D009154:Mutation; D054973:Perivascular Epithelioid Cell Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D049268:Positron-Emission Tomography; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics* / Q000378:metabolism; D014057:Tomography, X-Ray Computed; D000096985:Calponins
chemical_list: D002135:Calcium-Binding Proteins; D058965:MART-1 Antigen; D008840:Microfilament Proteins; D019009:Proto-Oncogene Proteins c-kit; D020796:Receptor, Platelet-Derived Growth Factor alpha; D000096985:Calponins
keywords: Gastrointestinal stromal tumor; KIT; Perivascular epithelioid cell tumor; Platelet-derived growth factor receptor