Primary myelofibrosis

Last revised by Yoshi Yu on 5 Oct 2023

Primary myelofibrosis is a myeloproliferative neoplasm in which the bone marrow is replaced with collagenous connective tissue resulting in progressive fibrosis. It is characterized by:

It usually affects the middle-aged to elderly, with a mean age of 60 years 6. The estimated prevalence is ~1:100,000. There may be a slight male predilection12 .

It is a chronic clonal stem cell disorder of neoplastic megakaryocytes and is considered a BCR-ABL1 (breakpoint cluster region-Abelson murine leukemia viral oncogene homologue 1)-negative myeloproliferative disorder 11.

Progressive bone marrow fibrosis is the result of collagen produced by non-neoplastic fibroblasts in response to inappropriate release of PDGF and TGF-ß from the neoplastic megakaryocytes 8.​

Most radiological features are a result of extramedullary hematopoiesis and seen in many systems.

  • osteosclerosis

    • diffuse pattern

    • no bony architectural distortion

    • typical distribution:

      • axial skeleton

      • ribs

      • proximal humerus and femur

    • bone scan may give "superscan" appearance

Prognosis is poor, with slow progression and death usually within 2-3 years. It can also transform into acute myeloid leukemia in a small number of patients 10.

General differential considerations include:

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Cases and figures

  • Case 1: with widespread decreased marrow signal
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  • Case 2
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  • Case 2
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  • Case 3
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  • Case 4
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  • Case 5
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  • Case 6: with hepatosplenomegaly
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  • Case 7: myelofibrosis with massive splenomegaly and infarct
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  • Case 8: acute SDH with myelofibrosis
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  • Case 9
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  • Case 10
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