Objective: Focal submucosal invasive colorectal cancers (submucosa-sm1) can be managed by endoscopic mucosal resection (EMR) as local lymph node metastasis (LNM) are rare. Lesions are usually flat, depressed or mixed. In deeper vertical submucosal invasion (sm2-3) LNM rates exceed 10-15%. EMR within this group can be complicated by perforation, noncurative resection and may leave LNM untreated. It is therefore essential to differentiate accurately focal sm1 disease from submucosal sm2/3 disease. The aim of this study was to evaluate the relationship between the invasive type V pit pattern using high-magnification-chromoscopic-colonoscopy (HMCC) and submucosal invasive depth for flat and depressed colorectal lesions.
Methods: Total colonoscopy was performed by a highly selected single endoscopist using the Olympus C240Z on 850 patients between January 2001 and July 2003. Kudo type V pits were identified using 0.05% crystal violet (CV) applied directly to the lesion using a steel tipped catheter. Type V pits were graded into class V(n)A-C as described by Nagata. Morphology was documented using the Japanese Research Society classification (JRSC). Histological sections, with reference to mucosal invasive characteristics, acquired using EMR or surgical excision were then compared with the pit pattern.
Results: Fifty-one lesions showed a type V pit pattern. The kappa coefficient of agreement between pit the type V pit pattern and histologically confirmed submucosal invasion was 0.51 (95% CI). Following resection, 97% of lesions were correctly anticipated to have sm2 + invasion using pit type Vn(B) and Vn(C) as clinical indicators of invasive disease. Specificity was low at 50% with an accuracy of 78%.
Conclusions: The type V pit pattern is useful for the in vivo staging of submucosal invasive depth in flat and depressed colorectal lesions and is as sensitive as conventional 7.5 MHz EUS. There was a tendency to over-stage lesions and hence the technique is limited by its low overall specificity.