The aims of this research are to validate and develop of therapeutic strategies for patients with colorectal lesions in real time through pCLE(probe-based confocal laser endomicroscopy). Endomicroscopy is a technique for obtaining histology-like images from inside the human body in real-time. Total objections are 311 patients.

Specific research topics are as below.

1. Diagnosis and classification of colon polyps through pCLE
2. Evaluation of the depth of invasion of colorectal cancer or lateral growth type tumor through the pCLE
3. Differential diagnosis of colorectal submucosal tumor through the pCLE
4. Differential diagnosis of ileocecal ulcers through the pCLE

The study will be conducted to measure sensitivity, specificity, accuracy, amphoteric predict of pCLE diagnosis, and calculate the agreement of prediction compared to the pathological findings of lesions Check diagnostic agreement of technical phrases which are derived, the matching degree between observers, and will develope a new classification method based on this.

Inclusion Criteria:

• Adults over 20 years old
• Patients with colorectal polyps
• Patients who undergo endoscopic submucosal dissection (ESD) due to lateral spreading tumors or early colorectal cancer
• Patients with submucosal tumor in colorectal cancer
• Patients with ileocecal ulcers
• Patients who consented to research

Exclusion Criteria:

• Patients who are impossible to biopsy or polypectomy due to underlying diseases.
• Patients who are not able to end the ESD because of a complication
• Patients who are already known the cause of ileocecal ulcers before the pCLE.
• Patients with contraindications to the use of disease fluorescent contrast agents
• Patients who did not consent to research
• Patients who are unsuitable for clinical trials in charge of the attending physician.