Rare incidental retroperitoneal schwannoma discovered as an adrenal mass upon pre-renal transplant workup: case report

Schwannomas are benign tumors originating from Schwann cells of the peripheral nervous system. They can occur anywhere in the body but are typically located in the head, neck, and flexor surfaces of the extremities. Retroperitoneal schwannoma is sporadic and accounts for only 4% of all retroperitoneal tumors and 3% of all schwannomas. The lesion was incidentally discovered in most patients upon investigation for another reason. We are reporting a case of a patient known to have hypertension, which was complicated by end-stage renal disease, and she started on hemodialysis in 2021. The patient planned for a kidney transplant, and a pre-renal transplant workup showed incidental findings of an adrenal mass. Further imaging and investigation revealed a non-functioning tumor. She planned for a laparoscopic adrenalectomy. Intraoperatively, the mass was retroperitoneal, close to the adrenal gland but not arising from it. Postoperative histopathology revealed a Schwannoma.