Most non-Hodgkin’s lymphomas are histologically highly malignant progressive β-cell lymphomas including immunoblast lymphomas and diffuse small anaplastic lymphomas. Non-Hodgkin’s lymphoma associated with HIV infection is often diffuse at the time of diagnosis and may involve extra-nodal tissues such as the bone marrow and gastrointestinal tract as well as sites invaded by Hodgkin’s lymphoma unrelated to HIV infection such as the central nervous system and body cavities. The pathogenesis of non-Hodgkin’s lymphoma associated with HIV infection can vary depending on the histologic subtype of the disease or the site of invasion. For example EBV, which causes B-cell clonal amplification, is detected in most Burkitt-like lymphomas and in almost all HIV infection-associated CNS lymphomas, but is rarely found in other immunoblast lymphomas. Similarly C-myc oncogene rearrangements and p53 oncogene mutations are typical presentations in diffuse small anaplastic lymphomas, yet are rare in immunoblast lymphomas. Clinical presentation Signs and symptoms: NHL must be differentiated from Hodgkin’s disease, acute and chronic leukemias, infectious mononucleosis, tuberculosis (especially primary tuberculosis with hilar lymph node enlargement), and other diseases causing lymph node enlargement including pseudolymphoma due to phenytoin sodium. The diagnosis can only be made by histological examination of the excised tissue. The usual histologic diagnostic criteria are disruption of the normal lymph node structure and invasion of the envelope and adjacent fat by typical tumor cells. Phenotypic examination can determine the cellular origin and its subtype, help determine prognosis, and may also be valuable in determining treatment options. The presence of leukocyte public antigen (CD45) is determined by an immunoperoxidase test (often used in the differential diagnosis of undifferentiated malignancies), while excluding metastatic carcinoma. This method can be used on fixed tissue to determine leukocyte common antigen. Most surface markers can also be examined on fixed tissue using the immunoperoxidase method, however fresh tissue is required for gene rearrangement and cytogenetic examination. Complications The organ infiltration is extensive, and both bone marrow and peripheral blood can be involved. The more frequent sites of invasion are the Wechsler pharyngeal ring, gastrointestinal tract, testes and intra-abdominal lymphatic tissues, as well as bone marrow tissue with leukemia-like blood changes. Examination tests 1. Histological examination: The diagnosis of this disease can only be made by histological examination of the excised tissue. The usual histological criteria for diagnosis are the destruction of the normal lymph node structure and the invasion of the envelope and adjacent fat by typical tumor cells. 2.Immunoperoxidase test: To determine the presence of leukocyte public antigen, while excluding metastatic carcinoma. This method can be used on fixed tissues to determine leukocyte common antigen. Most surface markers can also be examined on fixed tissues using the immunoperoxidase method, however, fresh tissue is required for gene rearrangement and cytogenetic examination. Diagnostic basis Clinical presentation: Painless lymph node enlargement predominates. Wechsler’s ring, gastrointestinal tract, testicular invasion, and intra-abdominal lymphadenopathy are more common than in Hodgkin’s disease. Hodgkin’s disease is often confined to one or two lymphatic regions at the beginning, and tends to expand sequentially to adjacent lymphatic regions as the disease progresses. Non-Hodgkin’s lymphoma more often invades the bone marrow and more often presents with leukemia-like changes in the blood picture. Specific systemic symptoms such as fever, weight loss, and night sweats are less common than in Hodgkin’s disease. Pathological histological examination: It is the main basis for confirming the diagnosis of this disease. Diseases that are easily misdiagnosed 1. Hodgkin’s disease. 2.Acute and chronic leukemia. 3. Infectious mononucleosis. 4, tuberculosis (especially primary tuberculosis with hilar lymph node enlargement), and other diseases causing lymph node enlargement including pseudolymphoma due to phenytoin sodium are distinguished. Prevention It is important to prevent malignant lymphoma by addressing the various factors that may lead to it. It is believed that loss of normal immune surveillance, tumorigenic effects of immunosuppressive drugs, active potential viruses and long-term application of certain physical (e.g., radiation) and chemical (e.g., antiepileptic drugs, adrenocorticotropic hormones) substances may lead to proliferation of lymphoreticular tissue and eventually malignant lymphoma. Therefore, it is important to pay attention to personal and environmental hygiene, avoid drug abuse, and pay attention to personal protection when working in harmful environments, etc.