title: A Case of Benign Schwannoma of the Transverse Colon with Granulation Tissue.
abstract: Schwannomas occurring in the gastrointestinal tract are rare, and among them, schwannomas of the large intestine are extremely rare. In this paper, we report a case of a macroscopically atypical schwannoma of the transverse colon. The case is a female aged 67. Stool occult blood test was positive, and colonoscopy revealed a protruded lesion resembling a type 1 carcinoma measuring 4 cm with a reddish and uneven surface on the transverse colon. The surface was smooth and lobulated in observation with indigo carmine spray, and granulation tissue was revealed by biopsies. CT of the abdomen showed an irregular mass, and clinical examinations could not rule out malignancy. Therefore, partial transverse colectomy with peripheral lymph node dissection was performed. Histologically, proliferation of spindle cells was observed originating from the muscularis propria, and most of the upper part of the lesion was replaced by granulation tissue. In immunohistochemical staining, S-100 protein and NSE were positive while KIT, CD34, desmin and smooth muscle actin were negative, and the tumor was therefore diagnosed to be a schwannoma. In addition, since the MIB-1 labeling index was low and virtually no mitosis was observed, it was diagnosed as benign tumor.
authors.affiliation: Department of Clinical Laboratory, Tokyo Women's Medical University, Medical Center East, Tokyo, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Tsunoda
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kato
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Rieko
authors.initials: R
authors.lastname: Yamada
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Mitsumaru
authors.forename: Hajime
authors.initials: H
authors.lastname: Yokomizo
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yoshimatsu
authors.forename: Kenji
authors.initials: K
authors.lastname: Ogawa
authors.forename: Motohiko
authors.initials: M
authors.lastname: Aiba
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Haga