A Retroperitoneal Mass Encasing the Renal Hilum Presenting as a Parapelvic Tumor: A Case Report with Laparoscopic Resection Approach.

Retroperitoneal masses are a rare condition that may be discovered incidentally in routine abdominal imaging. These lesions are commonly asymptomatic but may be associated with intestinal obstruction and rarely presented with acute abdomen. They may originate from the retroperitoneal organs, including the genitourinary or gastrointestinal tract, or originate primarily from retroperitoneal space, such as retroperitoneal fat, muscle, nervous system, and lymphatic system. The malignant masses are more common than benign masses, and sarcoma is the most malignant tumor in this space. We present a case with the hilar lesion of the left kidney that was managed with laparoscopic resection. The laparoscopy revealed that the mass completely enclosed the left renal hilum, but the mass was excised without any complication. The final pathologic report revealed a benign mesenteric cyst. Although most of the retroperitoneal mass had a malignant etiology, in cystic lesions in the renal hilar area, the benign mesenteric cyst may keep in mind the differential diagnosis of a mass in this anatomic region.