Lymphatic infiltration, or lymphocyte infiltration, is a pathological change in which lymphocytes gather in large numbers in diseased tissues and function after being stimulated. Lymphocyte infiltration can be seen in a variety of diseases, commonly inflammation, tumors and so on. When a local acute or chronic infection occurs, lymphocytes will be stimulated by the antigen and gather in large numbers towards the site of infection, through their own direct action or secretion and release of inflammatory factors to kill pathogens and cause tissue damage, at this time, the diseased part of the tissue is manifested as lymphatic infiltration. When a tumor appears in local tissues, lymphocytes will be activated under the action of tumor factors, gathering in the tumor and surrounding tissues, and continuously interacting with the tumor. When the lymphocytes themselves develop malignant changes, i.e., lymphoma, these lymphocytes also invade the surrounding tissues, forming a lymphocytic infiltrate. When lymphatic infiltration occurs, it is necessary to actively search for the cause of the disease, and it is recommended to seek timely medical treatment and standardize the treatment under the guidance of professional doctors.