Biological Characteristics And Surgical Effect Of Primary Retroperitoneal Schwannoma: A Report Of 59 Cases

Objective:To investigate the biological characteristics,surgical approaches and surgical effect of the primary retroperitoneal schwannoma(PRS)and analyze its risk factor for survival and recurrence.Methods:The clinical data and follow-up results of 59 patients with PRS in the affiliated hospital of Qingdao university from January 2002 to May 2016 were retrospectively analyzed.To compare the surgical outcomes and analyze prognostic factors of benign and malignant patients.Results:Of the 59 patients,24 cases(40.7%)were male and 35(59.3%)cases were female.The median age of the patients was 51 years old(range 23-77).There were 44(74.6%)patients who were diagnosed of benign PRS,and the malignant patients were 15cases(25.4%)with a benign to malignant ratio 2.93:1.40.7%(24/59)of the patients had abdominal discomfort,37.33%(22/59)were found in accessory examination,15.22%(9/59)found in physical examination,3.42%(2/59)had lower limb sensory disorder,1.7%(1/59)had chest pain,1.71%(1/59)had difficulty urinating.42.4%of patients had a close relationship with the large vessels of the abdomen,22.0%close to spine column or psoas.The average diameter of benign tumors was 6.7 cm,13.6%(6/44)were greater than 10cm,the mean diameter of malignant tumors was 14.8 cm,60%(9/15)were greater than 10cm.Malignant PRS are significantly larger than benign PRS.The diagnostic rate of preoperative imaging examination was 3.4%(2/59).All benign patients underwent radical resection with only one patient recurred in the postoperative 85 months.The multivisceral resection rate was 15.9%(7/44).The 1,3,5-year overall survival rates were all 100%.Among the malignant patients,80.0%(12/15)patients underwent radical surgeries.The degree of tumor differentiation(X~2=10.313,P=0.009)and tumor size(t=2.196,P=0.047)were correlated with the degree of radical excision.The multivisceral resection rate was 33.3%(5/15).The 1,3,5-year overall survival rates were 100%,77%,77%and the recurrence rates were 0%,11%,11%respectively.Only one patient recurred in the postoperative 85 months.The mortality rate in third year for malignant patients who did not undergo radical resection was 100%.The modus operandi of tumor resection is associated with survival rate of malignant patients(Log-Rank test,X~2=12.590,(49)(27)0.001).And the diameter of the tumor(X~2=0.692,P=0.406),sex(X~2=0.501,P=0.479),age(X~2=2.170,P=0.141)were not correlated with the prognosis of malignant patients.Multivariate analysis showed tumor diameter,sex,age,surgical radical resection were not the prognostic factors of malignant retroperitoneal schwannoma.The recurrence related factors of malignant patients were analyzed by Fisher’s exact probability method.Tumor diameter((49)=0.476),sex((49)=0.486g),age((49)=0.524),were not related to recurrence.The main complication were skin sensation and dysfunction of lower extremity caused by injury of femoral nerve during resection of psoas.The incidence of postoperative complications was 3.4%(2/59).The hospitalization time of open surgery was 7-34 days(mean 14 days)and the average hospitalization time of minimally invasive surgery was5-13 days(mean 9 days).The hospitalization time of patients with minimally invasive surgery was shorter than that of conventional open surgery,but the difference was not statistically significant(P=0.066).Conclusion:PRS is a rare and occult disease with low preoperative diagnosis.The incidence is increasing continuously with no significant difference between male and female.The tumors are always located in the area of the lumbar plexus nerve in the central axis of abdomen.The preoperative diagnosis rate is low,the difference of tumor size in benign and malignant patients is obvious and the high-grade differentiation and the small size are factors to achieve radical resection.The prognosis of the patients was related to the degree of radical operation.The prognosis of benign and malignant patients was significantly improved by radical resection.The prognosis of malignant PRS patients without radical resection was extremely poor.Although the location of retroperitoneal tumor was special,the patients who were properly selected could also be operated by laparoscopy,which had the advantages of good nerve protection,less bleeding during operation,short hospital stay and quick recovery.