Clinicopathologic Characteristics of Laterally Spreading Tumors in Colorectum

Ryu, Kwon Ho; Jang, Jae Young; Cha, Sang Woo; Cheon, Gab Jin; Kim, Jin Oh; Cho, Joo Young; Lee, Joon Seong; Lee, Moon Sung; Shim, Chan Sup; Kim, Boo Sung

Abstract

BACKGROUND/AIMS: Among colorectal neoplasms, laterally spreading tumors (LSTs) are defined as tumors over 10 mm in diameter that are low in height and grow superficially. We analyzed the clinicopathologic characteristics of LSTs in colorectum.
METHODS
Forty six LSTs were analyzed according to their endoscopic and pathologic findings.
RESULTS
Incidence of LSTs were 2.0% (46/2,276). Twenty two LSTs (47.8%) were less than 20 mm in diameter, 20 (43.5%) were 20-30 mm, 4 (8.7%) were larger than 30 mm. The most frequent location was rectosigmoid colon (54.3%), followed by ascending colon (21.7%). Morphplogic types were GH types 37.0% (17/46), MN types 30.4% (14/46) and F types 32.6% (15/46). Histologic types were tubular adenomas 65.2% (30/46), tubulovillous adenomas 26.1% (12/46) and villous adenomas 8.7% (4/46). The overall malignancy rate was 19.6% (9/46). Malignancy rates were 4.5% (1/22) in the lesions less than 20 mm, 30.0% (6/20) in 20-30 mm, 50.0% (2/4) in larger than 30 mm. Malignancy rates were 11.8% (2/17) in GH type, 21.4% (3/14) in NM type and 26.7% (4/15) in F type. Carcinoma invaded into the submucosa were present in one lesion of NM types and two of F type.
CONCLUSIONS
LSTs larger than 20 mm had high malignant potential, more than 30%. Furthermore, LSTs showed different clinicopathologic characteristics depending on the morphologic classification. NM or F type had higher malignant potential than GH type.