The reason for biopsy of peripapillary duodenal mucosal lesions is to clarify the nature of the lesion and to guide treatment. In the case of peripapillary duodenal mucosal lesions, if the nature of the lesion cannot be clarified endoscopically, then a biopsy may need to be considered. Biopsy is the use of excision, forceps, etc. to obtain lesions from the living body, and it is commonly used in cases of unknown etiology, suspected tumors, surgical resections, and screening for tumors. Biopsy can be observed under the microscope to clarify the relatively specific micro-morphological changes of the diseased tissue, which can then be used to determine the nature of the diseased tissue, understand the scope of the lesion, and can also be used to guide the treatment. Patients with peripapillary duodenal mucosal lesions requiring biopsy are advised to actively cooperate with their doctors in the examination process.