Malignant lymphomas are immune cell tumors that occur in lymph nodes and/or extra-nodal sites of lymphoid tissue and originate from malignant transformation of lymphocytes or histiocytes, and are a group of highly curable solid tumors. The main manifestations are lymphatic vessel rupture, painless lymph node enlargement, hepatosplenomegaly, and all tissues and organs of the body can be involved, with systemic symptoms such as fever, night sweats, emaciation and pruritus. Diagnosis 1. Diagnostic criteria: The diagnosis of lymphoma is based on pathological examination. Reed-Sternberg cells are characteristic of HL. R-S cells originate from B cells, are large in size, rich in cytoplasm, have light nuclear chromatin, and should have at least 2 nuclear lobules or nucleoli (if they are single nuclei, they are called Hodgkin’s cells), and have a positive immunophenotype for CD30 and CD15. According to other pathological features, HL is usually classified into 4 subtypes: nodular sclerosis, mixed cell type, lymphocyte predominant type and lymphocyte attenuated type; in WHO classification, another subtype is proposed: nodular lymphocyte predominant type, whose tumor cells resemble popcorn and are a variant of R-S cells. The basic pathological features of NHL are: loss of normal structure of lymph nodes and their replacement by tumor tissue; heterogeneity of proliferating lymphocytes; invasion of tumor cells into the lymphatic envelope. According to the morphological, immunological and molecular biological characteristics of tumor cells, NHL can be divided into many subtypes. After the diagnosis of lymphoma is confirmed, the disease stage should be made according to AnnArbor criteria. 2.Diagnostic evaluation: The diagnosis of lymphoma depends on pathological examination, and obtaining sufficient and suitable pathological specimens is the first condition for correct diagnosis. Usually, lymph node biopsy can be routinely performed in cases with superficial lymph node enlargement. In cases of enlarged mediastinal or intra-abdominal lymph nodes without superficial lymph node enlargement, a dissection or open thoracotomy is required to obtain a specimen. When deep lymph nodes are fused into a giant mass, puncture with a Tru-Cut needle is also quite satisfactory. In the case of splenomegaly only, when there is a high clinical suspicion of lymphoma, prompt splenectomy should be performed and a liver biopsy should be performed at the same time during the operation to get more diagnostic basis. In the case of liver lesions, liver puncture can be performed under CT or ultrasound guidance to obtain the desired liver tissue. Gastrointestinal microscopy and microscopic biopsy are very important for the diagnosis of gastrointestinal lymphoma, but the biopsy pathology and postoperative pathology results are not completely consistent, and the non-conformity rate of a group of cases in Peking Union Medical College Hospital is 25.8%. A small number of NHLs present with fever, jaundice, abnormal liver function, decreased whole blood cells or neuro-muscular symptoms in the early stage of the disease, without clear tumor mass or with contraindications to puncture or biopsy, when bone marrow examination is very important. Bone marrow aspiration and biopsy should be performed simultaneously and repeated several times if necessary, and new techniques such as chromosomal, immunophenotypic and gene rearrangement tests should be performed whenever possible to clarify the diagnosis early. Lymphoma should not be ruled out rashly if the diagnosis is not clear in one biopsy. In a group of 200 cases of NHL at Peking Union Medical College Hospital, 13.2% of the cases were diagnosed only after multiple biopsies. Therefore, it is recommended to consult with multiple pathologists in the following cases. (1) The pathology report of the biopsy specimen and the postoperative specimen are inconsistent. (2) Inconsistent pathology reports from outside the hospital and the hospital. (3) Inconsistent pathology reports of multiple biopsies. (4) Suspicious pathological findings that are not clinically consistent. There is no difficulty in the diagnosis of typical lymphoma. However, clinicians should pay sufficient attention to the extent and stage of the disease. When the diagnosis of lymphoma is confirmed by pathological examination, bone marrow examination, chest and abdominal CT, and full gastrointestinal barium meal imaging should always be performed as far as possible. Although ultrasonography is inexpensive and easy to perform, it has poor repeatability and lacks long-term preservation of images, so it is only suitable for primary screening and post-treatment follow-up.