(P 366) ABDOMINAL AORTA RESECTION EN-BLOC WITH PRIMARY RETROPERITONEAL SOFT-TISSUE SARCOMA AND BI-ILIAC GRAFT RECONSTRUCTION.

Objective: Nearly 15% of all adult soft-tissue sarcomas arise from the retroperitoneum. Complete surgical resection is the mainstay of treatment in localized tumors and local recurrence rates are closely related to the status of surgical margins. Therefore, it might be necessary to perform en-bloc resections in case of invasion of either surrounding tissues or adjacent organs. Similarly, major blood vessel involvement is challenging for sarcoma surgeons because vascular resection and immediate reconstruction is mandatory to obtain complete resection. This situation is another example of the need for a multidisciplinary approach to improve the management of soft-tissue sarcomas.
We present a case of retroperitoneal soft-tissue sarcoma resected en-bloc together with the infrarenal aorta and both common iliac arteries.

Methods: N/A (Operative and Procedural Video).

Results: A 54-year-old woman was referred to our surgical department because of a retroperitoneal mass found on abdominal computed tomography (CT) scan performed due to chronic and mild unspecific abdominal pain. Her medical history was significant only for hypertension and clinical examination was normal. CT scan showed a retroperitoneal soft-tissue mass with heterogeneous contrast enhancement measuring 101 x 141 x 84 mm with wide encasement of the infrarenal aorta (Inferior Vena Cava and Superior Mesenteric Artery were spared). The tumor was in contact with the left psoas muscle and compressed the left ureter producing proximal urinary tract dilation.
After discussing the case in a multidisciplinary tumor board, multiple CT-guided core biopsies were performed with a co-axial technique and 14G needle using a posterior approach. Histopathology study of the samples revealed a low-grade sarcoma. Based on this result, the decision was made for complete surgical resection with major vascular resection and reconstruction. The patient underwent en-bloc resection of the tumor together with the right psoas muscle, right nephrectomy, and vascular reconstruction using a bi-iliac polytetrafluoroethylene (PTFE) vascular graft. Immediately after surgery, thrombosis of the left branch of the vascular graft was observed requiring urgent thrombectomy and re-anastomosis on the same day. The patient subsequently developed acute renal failure treated with hemodialysis for 3 weeks. She was discharged on post-operative day 49 with normal renal function and no need for dialysis. Final histopathological examination confirmed a high-grade (FNCLCC Grade 2) biphasic synovial sarcoma and a new multidisciplinary evaluation recommended close follow-up without adjuvant treatment. After 7 years of follow-up, the patient remains alive without evidence of local recurrence or metastatic disease.

Conclusion: The quality of surgery is correlated with oncologic outcome in retroperitoneal soft-tissue sarcomas. Therefore, complete surgical resection with negative margins remains the cornerstone of sarcoma treatment.
In the retroperitoneal space, complex multivisceral resections are often required. Additionally, resection of the major vessels may be necessary to achieve a complete resection. In up to 14% of patients with primary retroperitoneal sarcoma this procedure is needed, as reported by the Trans-Atlantic Retroperitoneal Sarcoma Working Group (TARPSWG). Primary sarcomas of the aorta are very rare and the need for aortic resection and immediate reconstruction is more often (although rarely) required in patients that have adjacent tumors with secondary wide encasement or partial infiltration. Different techniques of vascular reconstruction can be used; when arterial resection is required primary anastomosis is usually not feasible because of the extent of the resection to obtain free margins. Major blood vessels - as in the case presented - are usually reconstructed with a prosthetic graft. The patency rate for prosthetic (PTFE) grafts used for reconstruction of large caliber arteries is reported to be higher than 90%. Moreover, it is well known that major vascular resections significantly increase postoperative morbidity (at least two-fold increased risk of adverse events). Finally, many studies report that there is no statistically significant difference in progression- free survival and local recurrence rate between patients with histologically proven vessel invasion and simple encasement. These data suggest that vascular involvement is a relevant technical issue in order to obtain local control rather than a negative prognostic factor per se.Major blood vessel involvement is not a contraindication for surgical resection of primary retroperitoneal sarcoma with curative intent.