Bone marrow reconversion

Bone marrow reconversion generates a red bone marrow pattern that is in reverse to the normal yellow-to-red distribution. 

Pathology

Bone marrow reconversion occurs when there is increased hematopoietic demand, which may be ^1,2:

• physiological
  • cigarette smoking
  • obesity
  • high endurance athletes
  • high altitude
  • post granulocyte-colony stimulating factor treatment
• pathological
  • severe chronic anemia, e.g. sickle cell disease, thalassemia, hereditary spherocytosis
  • diabetes mellitus
  • chronic respiratory disease

Radiographic features

MRI

Signal intensity will be that of normal red marrow being low T1 signal but still higher than skeletal muscle ^1,3. In the appendicular skeleton, it tends to be symmetrical and homogeneous, whereas in the axial skeletal it can be heterogeneous/multifocal ¹. Marrow reconversion occurs in the reverse order of normal red to yellow marrow conversion ⁴.

Differential diagnosis

• if homogeneous consider diffuse marrow infiltration ¹
• if heterogeneous consider ¹
  • skeletal metastases
  • multiple myeloma