The causes of enlarged lymph nodes in the mesenteric area and retroperitoneum include local inflammation, mesenteric lymph node tuberculosis and primary tumors of the intestinal tract. 1. Local inflammation: Inflammation of the abdominal intestines or acute and chronic inflammation of other organs can cause enlargement of mesenteric and retroperitoneal lymph nodes, accompanied by abdominal pain, diarrhea or other symptoms, and the enlargement of the mesenteric lymph nodes will subside on its own with the disappearance of the inflammation in the abdominal cavity. 2. Mesenteric lymph node tuberculosis: lymph node tuberculosis is often secondary to lymph node enlargement, low-grade fever, abdominal mass, abdominal pain, or even intestinal perforation, and the enlargement of lymph nodes is tuberculous enlargement. 3. Primary intestinal tumor: local lymph node metastasis of intestinal tumor will have obvious enlargement of mesenteric and retroperitoneal lymph nodes, with manifestations of blood in stool, abdominal pain and so on. If patients have the symptoms of enlarged lymph nodes in mesenteric area and retroperitoneum, it is recommended that they go to regular hospitals to find out the cause of the disease in time, and carry out treatment according to the cause of the disease, so as to avoid delaying the condition.