Myelofibrosis is a haematological disorder where there is the replacement of bone marrow with collagenous connective tissue and progressive fibrosis. It is also classified as a myeloproliferative disorder. It is characterised by:
- extramedullary hematopoiesis (EMH)
- progressive splenomegaly
- variable change in the number of granulocytes and platelets
It usually affects the middle-aged to elderly (mean age 60 years6). The estimated prevalence is at ~1:100,000.
Non-neoplastic fibroblasts produce collagen, which replaces normal bone marrow elements. This bone marrow fibrosis is a result of an inappropriate release of PDGF and TGF-ß from neoplastic megakaryocytes 8.
It can be broadly classified into:
- primary myelofibrosis, e.g. agnogenic myeloid metaplasia
- secondary myelofibrosis: marrow replacement from malignancy/toxins
Most radiological features are a result of EMH and seen in many systems.
- tends to be diffuse and there is a lack of architectural distortion
- frequent sites include
- axial skeleton
- proximal humerus and femur
- bone scan may give "superscan" appearance
- splenomegaly: can be massive
- evidence of portal hypertension 3
- from increased splenic blood flow
- from portal flow obstruction from the sinusoidal haematopoetic proliferation
- may show evidence of congestive cardiac failure due to anaemia 3
Treatment and prognosis
Prognosis is poor, with slow progression and death usually within 2-3 years. It can also transform into acute myeloid leukaemia (AML) in a small number of patients 10.
General differential considerations include:
- 1. Bond JR. Musculoskeletal case of the day. Myelofibrosis. AJR Am J Roentgenol. 1993;160 (6): 1330. AJR Am J Roentgenol (citation) - Pubmed citation
- 2. Guermazi A, De kerviler E, Cazals-hatem D et-al. Imaging findings in patients with myelofibrosis. Eur Radiol. 1999;9 (7): 1366-75. Eur Radiol (link) - Pubmed citation
- 3. Shaver RW, Clore FC. Extramedullary hematopoiesis in myeloid metaplasia. AJR Am J Roentgenol. 1981;137 (4): 874-6. AJR Am J Roentgenol (citation) - Pubmed citation
- 4. Choi H, David CL, Katz RL et-al. Case 69: extramedullary hematopoiesis. Radiology. 2004;231 (1): 52-6. doi:10.1148/radiol.2311020673 - Pubmed citation
- 5. Kaplan KR, Mitchell DG, Steiner RM et-al. Polycythemia vera and myelofibrosis: correlation of MR imaging, clinical, and laboratory findings. Radiology. 1992;183 (2): 329-34. Radiology (abstract) - Pubmed citation
- 6. Cloran F, Banks KP. AJR teaching file: Diffuse osteosclerosis with hepatosplenomegaly. AJR Am J Roentgenol. 2007;188 (3): S18-20. doi:10.2214/AJR.05.2141 - Pubmed citation
- 7. Gillard J, Schaefer-Prokop. Grainger's and Allison's Diagnostic Radiology. Churchill Livingstone. (2008) ISBN:0443101639. Read it at Google Books - Find it at Amazon
- 8. Kumar V, Fausto N, Abbas A. Robbins and Cotran pathologic basis of disease. Saunders. ISBN:0721601871. Read it at Google Books - Find it at Amazon
- 9. Saboo SS, Krajewski KM, O'Regan KN et-al. Spleen in haematological malignancies: spectrum of imaging findings. Br J Radiol. 2012;85 (1009): 81-92. doi:10.1259/bjr/31542964 - Free text at pubmed - Pubmed citation
- 10. Quintás-Cardama A, Kantarjian H, Pierce S et-al. Prognostic model to identify patients with myelofibrosis at the highest risk of transformation to acute myeloid leukemia. Clin Lymphoma Myeloma Leuk. 2013;13 (3): 315-318.e2. doi:10.1016/j.clml.2013.01.001 - Free text at pubmed - Pubmed citation