Extra-adrenal myelolipoma: report of two cases.

Myelolipomas are benign tumors composed of an admixture of mature adipose tissue and normal hematopoietic cells. The vast majority occur within the adrenal glands, but several extra-adrenal myelolipomas (EAMLs) have been reported. The typical EAML is a solitary, well-defined mass within the abdomen, most commonly in the retroperitoneal presacral area. EAMLs may produce symptoms related to their mass effect, but they are occasionally incidental findings. Most commonly, the patient is older than 40 years and has no hematologic abnormalities. It is important to distinguish EAMLs from other soft tissue tumors, in particular liposarcomas, myxoid malignant fibrous histiocytomas, and extramedullary hematopoietic tumors. We discuss two cases of EAML. The first was in the retroperitoneum of a 76-year-old woman. It is the largest EAML ever reported, measuring 26 cm x 15 cm x 11 cm. The second, a presacral mass in a 68-year-old man, was diagnosed preoperatively by percutaneous computed tomography-guided fine needle aspiration biopsy. Preoperative diagnosis facilitated surgical management in this case. We discuss the clinical, radiologic, and pathologic characteristics and the differential diagnosis of this rare entity.