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. 2014 Jan 1;8(1):1–12. doi: 10.3941/jrcr.v8i1.1551

Table 3.

Comparison between extra-adrenal myelolipoma (EAML), extra-medullary haematopoiesis (EMH) and Neurofibroma (as an example of neurogenic tumour)

Extra-adrenal myelolipoma Extra-medullary haematopoiesis Neurofibroma (Example of neurogenic tumors)
Definition Benign tumour composed of fat and myeloid tissues Formation of blood elements outside the bone marrow cavity Benign nerve sheath tumour
Etiology Still unclear

  • -Marrow failure

  • -Ineffective circulating mature blood elements

 Unknown or syndromic
Incidence Extremely rare Rare Uncommon
Pathological features
Site

  • -Presacral

  • -Retroperitoneal

  • -Other rare sites

  • -Spleen/liver

  • -Paraspinal

  • -Other sites: (any mesenchymal tissue)

  • -Posterior mediastinum

  • -May occur along any peripheral nerve
Multiplicity Usually single Multiple 10% multiple
Capsule Pseudocapsule Non capsulated Non capsulated
Macroscopic Yellow fat areas on cut section Discrete flesh coloured mass

  • -Solid tumour

  • -Cystic degeneration
Microscopic Megakaryocytes Marrow elements outside the bone marrow

  • -Nerve sheath cells

  • -Collagen bundles

  • -Myxoid degeneration
Associated (Related) conditions Usually non

  • -Haemoglobinopathies (thalassemia, sickle cell anaemia)

  • -Haemosiderosis (in case of repeated transfusions)

  • -Neurofibromatosis I

  • -other neurogenic tumours (e.g. optic glioma)

  • -Malignant transformation
Clinical features
Age peak 6th–8th decade 3rd–4th decade 3rd–4th decade
Demographics --

  • -Thalassemia: Mediterranean countries

  • -Sickle cell anaemia: African Americans

 --
Symptoms

  • -Asymptomatic

  • -Depending on the location symptoms from mass-effect possible

  • -EMH itself is asymptomatic

  • -May cause symptoms in case of spinal compression

  • -Asymptomatic

  • -Mass-effect

  • -Nerve entrapment

  • -Pain (due to malignant transformation)
Symptoms of associated conditions --

  • -Signs and symptoms of chronic anaemia

  • -Hepatosplenomegaly

  • -Von Recklinghausen’s disease:

  • .Café au lait spots

  • .Neurofibromatosis nodules
Treatment Asymptomatic lesions (confidently diagnosed by imaging) should be left alone

  • -Blood transfusion

  • -Hydroxyurea

  • -Irradiation

  • -Excision

 Surgical excision in localized lesions.
Prognosis Very good Excision is associated with high recurrence rate and may cause anaemic crisis Recurrence in case of multiple or plexiform lesions
Imaging features
General features Well marginated
Fat & myeloid tissues		 Well marginated
(Fatty deposition may occur in long standing lesions)
(Usually >5cm)

  • -Localized, diffuse, plexiform

  • -Dumbbell shape

  • -Smooth round appearance

  • -Cystic degeneration

  • -Calcification
X-ray (depending on site & size) Well demarcated mass Well demarcated mass Well demarcated mass
CT

  • -Fat: negative attenuation

  • -Myeloid: higher attenuation

  • -Homogenous hypodense

  • -Heterogeneous in case of fatty deposition

 Homogeneous hypodense
T1 WI

  • -Fat: hyperintense

  • -Myeloid: low signal

 Iso to mildly hyperintense to muscles Centre of the lesion have higher signal than periphery
T2 WI

  • -Fat: hyperintense

  • -Myeloid: moderate signal

 Iso-to mildly hyperintense to muscle Periphery has higher signal than the centre
Contrast Enhancement of myeloid components

  • -Homogenous mild enhancement

  • -Heterogeneous in case of fatty deposition

  • -Homogenous mild/moderate enhancement

  • -Target appearance
Scintigraphy Monoclonal antibodies directed against myeloid elements Technetium 99m sulfur colloid marrow scan FDG-PET
Higher SUV in malignant transformation
Other findings ---

  • -Hepatosplenomegaly

  • -Intramedullary hyperplasia:

  • .Thickened trabeculae

  • .Widened ribs.

 Neurofibromatosis:

  • .Cutaneous nodules

  • .Bone remodelling, deformities, erosions and scalloping

  • .Widened neuroforamina