title: IgG4-related disease of the ileocecal region mimicking malignancy: A case report.
abstract: BACKGROUND
  Immunoglobulin G4-related disease (IgG4-RD) is a systemic disease characterized by chronic fibrosing inflammation with abundant IgG4-positive plasma cells, and responds well to steroids. Previous reports of IgG4-RD have focused on pancreatic and extrapancreatic including the gastrointestinal tract, however, the colonic IgG4-RD is rare.
  
  
  METHODS
  We herein report the case of a 74-year-old female with edematous wall thickening of the terminal ileum to the lower ascending colon confirmed by several preoperative imaging studies, who underwent right hemi-colectomy for suspected malignant lymphoma. The resected specimen showed an irregular wall thickness with subserosal sclerosis, and the lesion was 10cm in length from the terminal ileum to the ascending colon. The patient was diagnosed with IgG4-RD by pathological examinations, which demonstrated an increased number of IgG4-positive plasma cells (150/HPF), and an elevated IgG4/IgG ratio (50%).
  
  
  CONCLUSIONS
  Gastrointestinal IgG4-RD appears to be difficult to diagnose prior to surgical resection because of its rarity, and the similarity of its features to malignancy. The measurement of the serum IgG4 levels, immunohistochemical examination of biopsy specimens and use of several imaging modalities might help us to diagnose the disease without surgical resection, and this disease can generally be treated with steroid therapy. However, surgical resection for IgG4-RD may still be also necessary for patients with concerns regarding malignancy or with intractable gastrointestinal obstruction caused by this disease.
  
  
  CONCLUSIONS
  Gastrointestinal IgG4-RD often mimics malignancy, and we should therefore consider this disease in the differential diagnosis of colonic lesions in order to optimize the treatment.
authors.affiliation: Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Japan. Electronic address: yukiharu0606@yahoo.co.jp.
authors.forename: Yukiharu
authors.initials: Y
authors.lastname: Hiyoshi
authors.affiliation: Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Oki
authors.affiliation: Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Zaitsu
authors.affiliation: Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Ando
authors.affiliation: Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Ito
authors.affiliation: Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Saeki
authors.affiliation: Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Morita
authors.affiliation: Department of Anatomic Pathology, Pathological Sciences, Graduate School of Medical Sciences, Kyushu University, Japan.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Yamamoto
authors.affiliation: Department of Gastroenterological Surgery, Graduate School of Medical Sciences, Kumamoto University, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Baba
authors.affiliation: Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Maehara
keywords: Colon; IgG4-related disease; Resection