Conclusion:
The RLS remains a rare tumor and should be suggested in cas of any large retroperitoneal tumor. It is an aggressive tumor with no typical presentation. The complete resection of the mass and a favorable histopathologic grade are positively associated with long-term disease-free survival. The complete (R0) surgical resection needs frequently an en-bloc resection of the tumor with ipsilateral involved or encased organs in particular the kidney. Criteria in favor of renal conservation are well encapsulated RLS, widely displaced kidney, well differentiated RLS sub-type and patient advanced age. An entirely encased kidney and ureteral invasion are not formal indications for associated nephrectomy.