Extra-adrenal myelolipoma.

Extra-adrenal myelolipomas are rarely reported lesions, with only 18 cases found in the world literature. We report a series of three cases, all occurring in women in an age range of 68 to 83 years (mean, 77 years). One patient presented with a pelvic mass while the other two cases were incidental findings at autopsy. All lesions were presacral in location, encapsulated, and not attached to adjacent structures. Sizes ranged from 6 to 12 cm in greatest dimension and from 72 to 330 g. Color was a variegated yellow to red-brown. Microscopically, all were composed of mature fat and focal collections of normal hematopoietic elements. The nature of these lesions is not known but most authors favor a choristomatous origin. They must be distinguished from extramedullary hematopoietic tumors seen in patients with severe anemias, myeloproliferative disorders, and skeletal disease.