- 1.5 per 100000, M=F, 50-60 years
- Myeloproliferative neoplasm of unknown etiology
- Clonal proliferation of hematopoietic stem cells
- Progressive bone marrow fibrosis leads to anemia, splenomegaly and extramedullary hematopoiesis
- JAK2 genetic abnormality in 55% cases
- Pancytopenia with abnormal red cell morphology
- Weakness, dyspnea, weight loss
- Increased risk of infection and gout
- Sites of extramedullary hematopoiesis: liver, spleen, lymph nodes, lung, choroid plexus, kidney
- Death in 2-3 years if allogenic stem cell transplant is not done. Leukemia may also develop
Imaging
- Bone sclerosis – diffuse, patchy, mainly in axial skeleton and in major long bone metaphyses
- Sclerosis – due to trabecular and endosteal new bone formation, this reduces marrow diameter
- Lucent areas in bone due to fibrous tissue
- Periosteal reaction – 1/3 of cases – at medial aspect of distal femur and proximal tibia
- Mixed sclerotic and lytic pattern – ‘superscan’ appearance
- MRI shows synovium infiltration by bone marrow elements
- Leukemic conversion shows extraosseous soft tissue mass
- Extramedullary hematopoiesis – hepatosplenomegaly, bilateral paravertebral masses in thorax, enlargement of ribs, pre-sacral mass. Fat containing non calcifying lesions. Fat signal suggests inactivity. Enhancement suggests activity
Read more
Guermazi, A., et al. “Imaging findings in patients with myelofibrosis.” European radiology 9.7 (1999): 1366-1375.
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