Successful Diagnosis of Invasion Depth in a Depressed Colon Neoplasm and Guidance for Treatment: Report of a Case

According to previous studies, the prevalence of non polypoid colorectal neoplasm (NP-CRN) in screening population is 4.2%-5.84% which is more associated with submucosal invasive carcinoma than polypoid colorectal neoplasm. Among them, depressed morphology is associated with higher malignant potential and invasiveness. Such subcategory of NP-CRN might arise via the so-called de novo carcinogenesis pathway. Due to subtle color change and small lesion size of NP-CRN, it is difficult to identify such a lesion. Suboptimal colonoscopy technique and inadequate bowel preparation contribute to the increase of colorectal cancer (CRC) and interval cancer incidence.The usefulness of image enhanced endoscopy (IEE) modality has good correlation with pathological invasion depth and guides treatment. Herein, we reported a case of 35 year-old woman who had a negative screening colonoscopy two years ago, but a 10 mm 0-IIa+IIc lesion of the transverse colon was found at the present screening colonoscopy. The lesion was characterized with IEE for morphological diagnosis and invasion depth evaluation. Under the impression of early colon cancer with deep submucosal invasion, she underwent laparoscopic right hemicolectomy and regional lymph node dissection. Pathology showed well to moderately differentiated adenocarcinoma with deep submucosal invasion and regional lymph node metastasis.