- Disease of the hematopoietic system
- Associated with fibrosis of the bone marrow and extramedullary hematopoiesis.
- Two forms are recognized: primary (idiopathic) and secondary.
- The most common sites of involvement are the spine, pelvis, skull, ribs, proximal end of the humerus, and proximal portion of the femur.
- Bone and joint pain, hemarthrosis and secondary gout are additional manifestations.
 Imaging Findings
 Plain Film
- Osteosclerosis is the predominant finding
- Uniform bone density or small areas of radiolucency may be present.
- Spine may demonstrate increased radiodensity, or condensation of bone at the superior and inferior margins of the vertebrae (sandwich vertebral body) can be encountered.
 MR imaging
- Fibrosis of the marrow is characterized by decreased signal intensity on both T1-weighted and T2-weighted spin-echo images.
Patient #1: CT images demonstrate diffuse sclerosis in this patient with myelofibrosis
Patient #2: MR images demonstrate diffuse decrease bone marrow signal intensity in this patient with myelofibrosis