Laterally spreading tumor: clinicopathological study in comparison with the depressed type of colorectal tumor.

ABSTRACT

AIM: To evaluate the difference between laterally spreading colorectal tumors (LSTs) with depression and depressed-type colorectal tumors. METHODS: Sixteen LSTs showing the appearance of non-distinct, gently sloping central depressions were compared clinicopathologically with 14 depressed-type tumors that were larger than 10 mm in size. RESULTS: The mean size of LSTs with depression was 13.5 +/- 3.4 mm, which was significantly larger than that of the depressed type colorectal tumors (11.2 +/- 1.5 mm). The invasion of the depressed-type colorectal tumors was significantly deeper than that of LSTs with depression, despite the larger size of the LSTs. The surface structures (pit patterns) of both types of tumors were apparently different; the pit patterns of LSTs with depression were almost of the type IIIL pit, while that of the depressed-type tumors were almost of type V pits (P < 0.01). Histologically, LSTs with depression appeared to grow in a superficial replacing manner on the edge of the lesions, while depressed-type tumors grew in an expanding manner. CONCLUSION: It seems appropriate that these LSTs with depression should be distinguished from depressed-type colorectal tumors and regarded as constituting a new clinical entity.