Characteristics of Laterally Spreading Colorectal Tumors according to Morphologic Classifications

Park, Su Bum; Song, Geun Am; Lee, Bong Eun; Ryu, Dong Yup; Kim, Dong Uk; Kim, Tae Oh; Kim, Gwang Ha

Abstract

BACKGROUND/AIMS
Laterally spreading tumors (LSTs) are similar in color to the adjacent mucosa, so they are difficult to recognize. This study aimed to investigate the features of LSTs by morphologic classification and find effective diagnoses and treatments.
METHODS
This retrospective study was done between March 2006 and August 2008. We reviewed patients' medical records, endoscopic findings, and histological findings.
RESULTS
A total of 151 patients met criteria for LSTs. Eighty-seven lesions (57.6%) were of the granular type. The most frequent location was ascending colon (37.1%), followed by rectum and sigmoid colon (36.4%). The cecum is a common site in the granular type, but the transverse colon is common in the nongranular type. The overall malignancy rate was 21.2%, and the malignant rate increased in proportion to size. Malignant rates were higher for the mixed nodular type (25.9%) and pseudo-depressed type (41.2%) than for the homogeneous granular type (3.0%) or flat elevated type (10.0%).
CONCLUSIONS
LSTs showed different clinicopathologic characteristics according to their morphologic classification. The homogenous type has a lower malignant potential. Piecemeal resection for those with a large diameter is possible, while the pseudo-depressed and mixed nodular types have a higher malignant potential and should receive en-bloc resection as soon as possible.