Multiple small lymph nodes in the retroperitoneum may be caused by inflammation and infection, or may be related to tuberculosis or tumor. 1. Inflammation: when bacterial or other microbial infection leads to inflammation of the abdominal cavity, under the stimulation of inflammation, the patient may have fever, fatigue, enlarged lymph nodes, etc. CT examination may indicate that there are multiple lymph nodes in the retroperitoneum. Common inflammatory diseases of the abdominal cavity include pancreatitis, appendicitis and so on. 2. Tuberculosis: Multiple small retroperitoneal lymph nodes are often associated with tuberculosis infection, and tuberculosis infection in the abdominal cavity, gastrointestinal tract, lungs and other places may lead to the symptoms of multiple small retroperitoneal lymph nodes, accompanied by low-grade fever, emaciation, night sweats and enlarged lymph nodes. 3. Tumor: lymphatic metastasis of malignant tumors, lymphoma, lymphocytic blood disease and so on may invade the retroperitoneal lymph nodes, resulting in the enlargement of these lymph nodes. When patients are found to have multiple small retroperitoneal lymph nodes, they should consult the doctor in time, complete the examination, make a clear diagnosis and then follow the doctor’s instructions to be treated accordingly.