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Everything you need to know about Computed Tomography (CT) & CT Scanning

Adrenal Myelolipoma

Key facts

  • benign tumor incidentally discovered on CT usually in older patients
  • present in 0.2-0.4% of patients based on autopsy series
  • are never functioning and do not secret any hormones
  • case reports show that tumors can spontaneously bleed or become necrotic. If they bleed can present symptomatically
  • key is to recognize the benign nature of these lesions and avoid unnecessary workup for an incidental adrenal mass

CT Findings

  • most tumors are simply large fatty masses while other tumors have a variable amount of fat visible.
  • if no fat is present you can not make the diagnosis on CT
  • foci of calcification not uncommon
  • although most tumors are 2-4 cm in size others can be 10 cm or greater (20 cm masses have been reported)

MR Findings

  • findings will vary depending on the amount of fat present but typically are hyperintense on T1-weighted images


  • echogenic mass in the adrenal bed
  • if extensive fat component to tumor then hard to distinguish from the retroperitoneal fat


  • tumor composed of bone marrow elements including myeloid and erythroid cells and fatty elements.
  • composed of variable amounts of mature adipose tissue

Clinical presentation

  • usually as an incidental finding
  • may present with an acute abdomen due to spontaneous hemorrhage (rare)

Differential Diagnosis

  • adenoma- usually of low CT attenuation but not as much visible fat as a myelolipoma
  • retroperitoneal liposarcoma- tumors may grow up to adrenal space and simulate a Myelolipoma especially if findings detected on a chest CT where the entire mass is not scanned
  • renal angiomyolipoma- projected off superior pole of kidney can simulate a myelolipoma
  • adrenal cyst- cysts are water density and do not contain fat
  • metastases- metastases are of higher CT attenuation


  1. Adrenal Myelolipoma
    Cyran KM, KenneyPJ, Memel DS et al.
    AJR 1996;166:395
  2. The natural history and treatment of Adrenal Myelolipoma
    Han M, BurnettAL, Fishman EK et al
    J Urol 1997;157:1213
  3. Characterization of Adrenal Masses Using MR Imaging with Histopathologic Correlation
    Heinz-Peer G, Honigschnabl S, Schneider B et al.
    AJR 1999;173: 15-22
© 1999-2020 Elliot K. Fishman, MD, FACR. All rights reserved.