Laparoscopic resection of a retroperitoneal schwannoma posterior to the renal artery.

Background: Retroperitoneal schwannoma is usually asymptomatic, and is often found incidentally during physical examination. It is easy to be misdiagnosed as paraganglioma, retroperitoneal malignant tumor and giant lymphocyte hyperplasia. Accurate preoperative diagnosis is helpful for clinicians to make surgical plans and preoperative preparations. This paper reports a case of retroperitoneal schwannoma. Preoperative imaging suggested a neurogenic tumor behind the left renal artery. The treatment was laparoscopic retroperitoneal tumor resection. The postoperative pathological diagnosis was retroperitoneal schwannoma.

Methods: The 52-year-old female patient was admitted to the hospital due to a left retroperitoneal tumor. Preoperative CT and MRI showed neurogenic tumor. After patient authorization, left retroperitoneal tumor resection was performed under laparoscopy. The postoperative pathological diagnosis was retroperitoneal schwannoma. The patient was followed up for 1 year without recurrence or metastasis. The CT features of retroperitoneal schwannoma may be lower than that of the muscle tissue at the same level, with uneven density, cystic lesions, hemorrhage, calcification and other characteristics. Enhanced CT can show progressive enhancement, mild to moderate enhancement in the arterial phase and moderate enhancement in the delayed phase. MRI showed slightly high signal intensity in the center of T2WI lesions, obvious high signal intensity at the edge, and high signal intensity on DWI. The diagnosis of retroperitoneal schwannoma depends on postoperative pathological examination. S-100 protein is one of its specific markers, and most of them are positive. Retroperitoneal schwannoma is mostly benign, but there are also some patients with malignant tumors. The first choice of treatment is complete resection of the tumor, and the tumor margin can also be negative by removing part of the normal adjacent tissue. The survival rate of patients with complete resection can reach 100 %, and the recurrence rate of patients with incomplete resection is about 5-10 %.

Conclusions: Retroperitoneal schwannoma is a relatively rare retroperitoneal tumor. Enhanced CT can show progressive enhancement, mild to moderate enhancement in the arterial phase and moderate enhancement in the delayed phase. MRI showed slightly high signal intensity in the center of T2WI lesions, obvious high signal intensity at the edge, and high signal intensity on DWI. The diagnosis of retroperitoneal schwannoma depends on postoperative pathological examination, and S-100 protein is one of its specific markers. Retroperitoneal schwannoma is mostly benign, but there are also some malignant tumors. The treatment of retroperitoneal schwannoma is the first choice to completely remove the tumor.