(A) Definition Intraepithelial neoplasia, also called intraepithelial neoplasia, refers to the appearance of heterogeneous proliferation (atypical proliferation) in part or all of the cells in the epithelial layer. The appearance of heterogeneous proliferation throughout the epithelium is considered as carcinoma in situ. (2) Classification 1. low-grade intraepithelial tumor/low-grade intraepithelial neoplasia: intraepithelial heterogeneous proliferation <1/2 layer 2. high-grade intraepithelial tumor/high-grade intraepithelial neoplasia: intraepithelial heterogeneous proliferation >1/2 layer (3) Surgical treatment options for such patients 1. for low-grade intraepithelial tumor/neoplasia: endoscopic mucosal resection of ESD, or follow-up review (endoscopic review at 2-3 months interval) . Rationale: Foreign literature shows that low-grade intraepithelial tumors have a 20-30% cancer rate with 2-4 years follow-up. 2. For high-grade intraepithelial tumors/neoplastic lesions ① Combine with what is seen in the endoscopy of the gastrointestinal tract, if there are no malignant features, only mucosal erosion, erythema, etc. Suggestion: review again in the near future (within 1-2 weeks), or communicate with the patient before surgery. ② Combine with the endoscopic view of the gastrointestinal tract, if there are malignant features, such as obvious huge ulcers, bulging neoplasm, etc. Recommendation: direct surgical resection. Rationale: Foreign literature shows that high-grade intraepithelial tumors have a cancer rate of about 80% with 4-5 months follow-up. Note: For biopsy pathology of high-grade intraepithelial tumors, one should be alert to the possibility of cancer already present.