Multiple enlarging hepatic and retroperitoneal myelolipomas in the setting of Cushing disease

Myelolipomas are benign tumours typically occurring in the adrenal glands, made up of fat and trilineage haematopoeitic cells resembling bone marrow. Their aetiology is not well understood; however, they have a clear association with elevated serum adrenocorticotropic hormone (ACTH). Extra-adrenal myelolipomas are rare, and to our knowledge there are no previously reported cases of multiple enlarging hepatic and retroperitoneal myelolipomas in the setting of Cushing disease. We present the case of a patient with an ACTH-producing pituitary adenoma who developed multiple enlarging fat containing lesions in the liver and retroperitoneum, which were histologically proven multifocal myelolipomas.