IV. Damage to nerve tissue Chenghua Luo, Center for Retroperitoneal Tumors, Peking University International Hospital Retroperitoneal tumors originating from nerve tissue include neurofibroma and nerve sheath tumors from spinal nerve (malignant ones are malignant neurofibroma and malignant nerve sheath tumors), and paraganglioma (malignant paraganglioma) from sympathetic nervous system. Benign neurofibromas are more common and usually grow larger before being detected. Most are not difficult to remove. However, the base of the tumor is often located at the intervertebral foramen, and a more complete removal of the tumor may result in injury to the nerve. If multiple nerves are injured, the corresponding nerve injury symptoms may occur. Neurofibromas sometimes have their bases in the spinal canal and require a joint effort with a neurosurgeon to remove the outer portion of the spinal canal before removing the inner portion. Nerve sheath tumors are similar to neurofibromas and are easier to remove. However, malignant neurofibromas or malignant nerve sheath tumors are much more difficult to remove and have a greater chance of nerve damage. A paraganglioma is slower growing, but it is located in the midline and can sometimes encircle the abdominal aorta. It is very difficult to resect. In our hospital, we met a case of paraganglioma located in the middle of the epigastrium, which had undergone an exploratory operation at the age of 3, but could not be removed because the tumor was behind the pancreas and partially encircled the abdominal aorta. Since the patient did not have any conscious symptoms, she was allowed to live with the tumor. Another patient, aged 48, was found to have a huge retroperitoneal tumor in the right upper abdomen after surgical exploration in another hospital 20 years ago, which could not be resected and was biopsied as a paraganglioma. Retroperitoneal tumors located in the pelvis can often compress the femoral nerve or sciatic nerve, and tumors of myogenic origin have a higher chance of nerve compression. We have encountered many cases where the femoral nerve was severely displaced. It was necessary to be very gentle when separating the nerve from the tumor, and even so, some patients showed damage to the femoral nerve after surgery, and the symptoms gradually disappeared after about 3 months. However, in some patients, the tumor completely encapsulated the femoral nerve or even the nerve passed through the tumor. This type of tumor had to remove the femoral nerve together, resulting in complete loss of function of the femoral nerve. After surgery, the quadriceps muscle cannot contract. The patient has to walk with the help of crutches. However, after one to two years of observation, some patients can walk without crutches. No further treatment is required. Otherwise, it is possible to surgically transfer some of the flexor muscles to the extensor muscles, which can correct the inability to extend the knee. Some retroperitoneal tumors may grow from the sciatic foramen to the posterior and compress the sciatic nerve. The sciatic nerve is easily damaged during surgery, but usually only partially, and rarely the sciatic nerve is completely removed. This type of injury can result in foot drop. Depending on the severity of the injury, there can be varying degrees of recovery. From the book “Retroperitoneal Tumor”, edited by Luo Chenghua, Director, Department of General Surgery, Peking University International Hospital