Giant presacral myelolipoma.

Myelolipomas are benign tumors composed of hematopoietic tissue and mature fatty tissue and occur primarily in the adrenal glands. Extra-adrenal sites for these tumors are rare. To date 37 cases have been reported in the literature with more than half of these lesions being presacral in location. The purpose of this report is to raise awareness of this unusual tumor when formulating a differential diagnosis for retroperitoneal tumors. Presacral myelolipomas are easily confused with both primary and secondary malignant retroperitoneal tumors, which are far more common and aggressive neoplasms. Particular radiographic and histologic qualities distinguish this tumor from invasive malignancy. A case report is presented with a review of the literature on extra-adrenal myelolipomas.