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Int J Clin Exp Pathol 2013;6(3):349-357

Original Article
Histopathologic study of the rectum in 1,438 consecutive rectal specimens in a single
Japanese hospital: I. benign lesions

Tadashi Terada

Department of Pathology, Shizuoka City Shimizu Hospital, Shizuoka, Japan

Received September 20, 2012; Accepted December 15, 2012; Epub February 15, 2013; Published March 1, 2013

Abstract: The author investigated histopathology of 1,438 consecutive rectal specimens in the last 10 years of our pathology laboratory in
Japan. A computer review of pathologic reports was done. Observations of pathologic slides were performed, when appropriate. The rectal
specimens were composed of 1,022 benign lesions and 416 malignant lesions. The 1,022 benign lesions were composed non-specific
proctitis (n=460, 45%), adenoma (n=248, 24%), ulcerative colitis (n=98, 10%), hyperplastic polyp (n=54, 5%), carcinoma in adenoma (n=40,
4%), rectal ulcer (n=37, 4%), serrated adenoma (n=24, 2%), hyperplastic nodule (n=21, 2%), Crohn’s disease (n=9, 1%), ischemic proctitis
(n=8, 0.8%), mucosal prolapse syndrome (n=7, 0.6%), juvenile polyp (n=6, 0.6%), lymphoid hyperplasia (n=5, 0.5%), lipoma (n=4, 0.4%) and
amebic dysentery (n=2, 0.2%), and mature cystic teratoma (n=1, 0.1%). In this article, histopathological features of these benign lesions were
described in details. In particular, adenomas were classified into adenomas with mild, moderate, and severe atypia, serrated adenoma, and
carcinoma in adenoma. The later are mainly seen in large adenoma with severe atypia. Ulcerative colitis was characterized by continuous
lesion, crypt abscess, abnormal branching, and deletion of goblet cells. Crohn’s disease was characterized by transmural inflammation and
epithelioid granulomas. Ischemic colitis was characterized by ischemic necrotic changes and pseudomembrane formation. Mucosal prolapse
syndrome was characterized by abnormal muscle in the mucosa (fibromuscular obliterance). Juvenile polyp was characterized by abnormal
dilations of the crypts. Lymphoid hyperplasia must be differentiated from MALT lymphoma. Lipoma was ordinary lipoma without lipoblasts.
Amebic dysentery was characterized by ulcer and presence of histiocyte-like entamoeba histolitica. Mature cystic teratoma was characterized by
hairs and other elements of skin and mesodermal and endodermal components. (IJCEP1209016).

Keywords: Colon, benign lesions, histopathology

Address correspondence to: Dr. Tadashi Terada, Department of Pathology, Shizuoka City Shimizu Hospital, Miyakami 1231 Shimizu-Ku, Shi-
zuoka 424-8636, Japan. Tel: 81-54-336-1111; Fax: 81-54-336-1315; E-mail: piyo0111jp@yahoo.co.jp