Perirenal extra-adrenal myelolipoma.

Myelolipomas are rare tumors consisting of both adipose and hematopoietic tissue and are typically found within the adrenal gland. Extra-adrenal involvement is rare, especially those tumors involving the perirenal space and collecting system. We report a case of a patient with an incidentally discovered perirenal mass that was initially concerning for a retroperitoneal liposarcoma. Following surgical resection and pathological analysis, the lesion was found to be an extra-adrenal myelolipoma. This case report and review of the literature demonstrates the importance of the proper work-up and management of perirenal lipoma variants while addressing the issues of tissue biopsy, surgical intervention, and pre- and post-operative surveillance.