Adrenal myelolipoma simulating a retroperitoneal malignant neoplasm.

We describe a case of a large myelolipoma (15 by 12 cm. maximum diameter) that was removed surgically and resembled clinically and semeiologically a malignant retroperitoneal tumor. The patient also had chronic pancreatitis and cholelithiasis. Experimental findings, as well as the frequent association of myelolipomas (usually small) with several chronic diseases, suggests that the adrenal myelolipoma is not a true neoplasm but, rather, a choristoma or, perhaps even more likely, a hyperplastic and/or metaplastic lesion.