Extraadrenal myelolipoma.

A rare case of presacral myelolipoma surgically resected from a 72-year-old woman, who also had megaloblastic anemia and brest carcinoma, is described and compared with mass-forming extramedullary hematopoiesis, and other reported cases of extra-adrenal myelolipoma. Extra-adrenal myelolipoma should be morphologically differentiated from mass-forming extra medullary hematopoiesis. The former is encapsulated or well-circumscribed, is composed of fat cells, and has normal marrow hematopoietic elements. The latter lacks circumscription, and fat is not an integral component of the process. Clinically, myelolipoma is usually asymptomatic, and shows no consistent associated disease process, while mass-forming extramedullary hematopoiesis is usually symptomatic, and is associated with myeloproliferative disorders, hemolytic anemia, or severe skeletal diseases.