| Theme |
New Development of Laterally Spreading Tumor |
| Title |
Definition and Subclassification of LST in Relation to Clinical Significance |
| Author |
Kaoru Takabayashi |
Division of Gastroenterology and Hepatology, Dept. of Internal Medicine, National Hospital Organization Tokyo Medical Center |
| Author |
Toshio Uraoka |
Division of Gastroenterology and Hepatology, Dept. of Internal Medicine, National Hospital Organization Tokyo Medical Center |
| Author |
Motohiko Kato |
Division of Gastroenterology and Hepatology, Dept. of Internal Medicine, National Hospital Organization Tokyo Medical Center |
| Author |
Yasutoshi Ochiai |
Division of Gastroenterology and Hepatology, Dept. of Internal Medicine, National Hospital Organization Tokyo Medical Center |
| Author |
Naohisa Yahagi |
Division of Research and Development for Minimally Invasive Treatment, Cancer Center, School of Medicine, Keio University |
| [ Summary ] |
The term "laterally spreading tumor" (LST) was defined as a colorectal tumor that spreads laterally to more than 10 mm in diameter. LSTs are classified into two types according to their morphology, the granular type (LST‒G) and the non‒granular type (LST‒NG). Each type has two sub‒groups：LST‒G includes a homogeneous type and a nodular mixed type, and LST‒NG includes both a flat‒elevated type and a pseudo‒depressed type. Usually, the homogeneous type of LST‒G with submucosal (SM) invasion is quite rare, but the nodular mixed type of LST‒G has a higher frequency of SM invasion when it grows larger than 40 mm, and the deepest penetration occurs under part of the large nodule. The flat‒elevated type also has a higher frequency of SM invasion when it grows larger than 40 mm, and the pseudo‒depressed type has a higher frequency of SM invasion when it grows larger than 20 mm. In this report, we explain the clinical significance of LST sub‒classification, including the relationship with clinicopathological features. |