Diagnosis of the level of depth in superficial depressed-type colorectal tumors in terms of stereomicroscopic pit patterns.

We investigated the relationship between stereomicroscopic pit patterns and histological structures in 93 lesions of superficial depressed-type colorectal tumors to assess the possibility of diagnosing the level of invasion by the pit patterns. All 9 lesions with Va (amorphous)-type pit pattern showed massive invasion into the submucosal layer (sm2, sm3). Massive invasion into sm was observed in 66.7% (6/9) of lesions with Vi (irregular)-type pit pattern, whereas 22.2% (2/9) of the lesions invaded the shallow layer of the submucosa (sm1) and 11.1% (1/9) were limited to the mucosa. Among the lesions with pit patterns other than Va and Vi, 93. 3% (70/75) were limited to the mucosa, whereas 6.7% (5/70) invaded the submucosal layer, but all were limited to sm1. These findings show that stereomicroscopic analysis of the pit patterns of the superficial depressed-type colorectal tumors is useful for diagnosing the level of invasion.