Multiple small lymph nodes in the abdominal cavity and retroperitoneum may commonly be due to tuberculosis, infection, or neoplastic disease. 1. Tuberculosis: tuberculosis caused by Mycobacterium tuberculosis infection will cause enlargement of abdominal cavity and retroperitoneal lymph nodes. Accompanied by low fever, night sweats, emaciation and other symptoms of tuberculosis poisoning. It should be treated with appropriate anti-tuberculosis drugs, such as isoniazid, rifampicin and so on. 2. Infection: when virus or bacteria and other microorganisms infect the human body, the lymphatic tissue as the immune organ proliferates and enlarges in order to resist the infection, which can be manifested as multiple small lymph nodes. Mostly seen in children’s respiratory tract infection or adult chronic colitis and other diseases. 3. Tumor disease: lymphoma, lymphocytic leukemia, malignant tumor abdominal cavity and retroperitoneal lymphatic metastasis, may lead to enlargement of these lymph nodes. If you find multiple small lymph nodes in the abdominal cavity and retroperitoneum, you should consult the doctor in time, complete the examination, make a clear diagnosis and then follow the doctor’s instructions to avoid the delay of the condition.