A case of perirenal extra-adrenal myelolipoma mimicking liposarcoma.

Myelolipoma is a benign tumor composed of mature adipose tissue and normal hematopoietic components. It usually occurs in the adrenal glands but rarely in the extra-adrenal region. However, it is difficult to differentiate extra-adrenal myelolipoma from well-differentiated liposarcoma on the basis of the radiological findings. We report the case of a 66-year-old male with perirenal and extra-adrenal myelolipoma who underwent radical tumor resection with nephrectomy after a preoperative diagnosis of liposarcoma. Intraoperative assessment by the surgeon and intraoperative pathological evaluation are important considering the divergent prognoses of myelolipoma and liposarcoma.