Musculoskeletal ImagingMyelofibrosis
a disease of the haematopoietic system of undetermined cause that is associated with
fibrosis of the bone marrow and extramedullary haematopoiesis. Two forms are recognized: primary (idiopathic) and secondary.
On radiographs, osteosclerosis is the predominant finding, but both osteolytic lesions and normal or osteopenic bone are also observed. The most common sites of involvement are the spine, pelvis, skull, ribs, proximal end of the humerus, and proximal portion of the femur. Uniform bone density or small areas of radiolucency may be present. The spine may demonstrate increased radiodensity, or condensation of bone at the superior and inferior margins of the vertebrae (sandwich vertebral body) can be encountered.
Bone and joint pain, haemarthrosis and secondary gout are additional manifestations.
The abnormalities in myelofibrosis are well shown by MR imaging. Fibrosis of the marrow is characterized by decreased signal intensity on both T1-weighted and T2-weighted spin-echo images. The same pattern of signal abnormality as in the axial skeleton also occurs in the tubular bones.
Acute megakaryoblastic leukaemia is also known as malignant myelofibrosis. This disease is characterized by anaemia, pancytopaenia and diffuse marrow fibrosis. In children, radiolucency in the metaphyseal regions of tubular bones and osteolytic lesions are seen. The degree of periostitis can be profound. In adults, focal or diffuse bone sclerosis is observed.
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