Even if the enlarged lymph nodes are temporarily reduced after anti-inflammatory and anti-TB treatment, if they increase again, pathological biopsy should be performed in a timely manner. If the enlarged lymph nodes are reactive hyperplasia after several biopsies, close follow-up should be performed. In patients with only mediastinal and retroperitoneal lymph nodes enlargement, lumpectomy should be performed promptly after a comprehensive examination, and open chest and open abdominal exploratory surgery can also be used if necessary to obtain diseased tissues for pathological examination. For patients with prolonged fever, night sweats and wasting, even if they are not accompanied by enlarged lymph nodes on the body, attention should be paid to exclude ML. Second, pathological diagnosis Combining histomorphology, immunohistochemistry and molecular biology techniques, most patients can be clearly diagnosed and typed. The following points should be noted when cutting biopsy tissue. The lymph nodes on the surface of the body should be selected as rapidly growing, full and tough enlarged lymph nodes, and removed as completely as possible, and not selected for cytological examination by needle aspiration aspiration or needle aspiration biopsy. As far as possible, select lymph nodes with small areas disturbed by inflammation for biopsy, such as supraclavicular, cervical, axillary, and supra-sliding lymph nodes. Intraoperative compression of the tissue should be avoided, and the tissue should be fixed as soon as possible after excision. When gastroscopic biopsy is performed in patients suspected of gastric lymphoma, sufficient submucosal tissue should be clamped as much as possible. PET examination is very useful for staging, determining treatment effect and prognosis. IV. Laboratory tests Routine blood tests, blood biochemistry and sedimentation, and lactate dehydrogenase are also well used.