Myelofibrosis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sujit Routray, M.D. [2]
Overview
Myelofibrosis is a hematological disorder in which the bone marrow is replaced with collagenous connective tissue and progressive fibrosis, replacing the bone marrow with a scar tissue and hence disrupting the normal production of blood cells which leads to pancytopenia.[1] It is also classified as a myeloproliferative disorder.[2] The term myelofibrosis alone usually refers to primary myelofibrosis (PMF), also known as chronic idiopathic myelofibrosis (CIMF); the terms idiopathic and primary mean that the disease is of unknown or spontaneous origin. This is in contrast with myelofibrosis that develops secondary to polycythemia vera, essential thrombocythaemia, leukemia, or lymphoma (secondary myelofibrosis). Myelofibrosis is a form of myeloid metaplasia, which refers to a change in cell type in the blood-forming tissue of the bone marrow, and often the two terms are used synonymously. Genes involved in the pathogenesis of myelofibrosis include JAK2, CALR, and MPL.[3] Myelofibrosis must be differentiated from other diseases that cause diffuse bone sclerosis, such as sickle cell disease, hyperthyroidism, sclerosing bone dysplasia, osteoblastic metastases, and Paget's disease.[4][5] Myelofibrosis must be differentiated from other diseases that cause splenomegaly, such as anemia, CML, polycythemia rubra vera, cirrhosis, infections, neoplastic, and lipid storage disorders.[4][6] The prevalence of myelofibrosis is approximately 1 per 100,000 individuals worldwide. Myelofibrosis is a disease that tends to affect the middle-aged and elderly population. The mean age at diagnosis is 60 years.[7] Males are more commonly affected with myelofibrosis than females. The male to female ratio is approximately 1.5 to 1.[8] Myelofibrosis usually affects individuals of the Ashkenazi Jews race. African American, Latin American, and Asian individuals are less likely to develop myelofibrosis.[9] Common risk factors in the development of myelofibrosis may be age, other myeloproliferative disorders, radiation, or industrial chemical exposure.[10] Myelofibrosis has a very indolent course. If left untreated, myelofibrosis may progress to develop acute myelogenous leukemia, thrombohemorrhagic events, and progressive marrow failure. Common complications of myelofibrosis include infections, bleeding, hepatic failure, heart failure, and gout.[11][12][13][14] Prognosis is generally poor and the median survival for myelofibrosis is 3.5 years to 5.5 years, but patients younger than 55 years have a median survival of 11 years.[13] According to the World Health Organization (WHO) diagnostic criteria for primary myelofibrosis, polycythemia vera, and essential thrombocythemia, the diagnosis of primary myelofibrosis is made when all three of the following major diagnostic criteria and at least two minor criteria are met.[15][16] Symptoms of myelofibrosis include left upper quadrant abdominal pain, bruising, easy bleeding, pale skin, and frequent infections.[17][18][19] Common physical examination findings of myelofibrosis include pallor, petechiae, lymphadenopathy, hepatomegaly, and splenomegaly.[19] Laboratory findings consistent with the diagnosis of myelofibrosis include decreased red blood cells, normochromic normocytic anemia, tear-drop shaped RBCs, thrombocytopenia, and raised levels of lactate dehydrogenase.[20] X-ray may be helpful in the diagnosis of myelofibrosis. Findings on x-ray suggestive of myelofibrosis include osteosclerosis at different sites of the body, which tends to be diffuse and devoid of architectural distortion.[21] CT scan and MRI may be helpful in the diagnosis of myelofibrosis. Findings on CT scan suggestive of myelofibrosis include diffuse bone sclerosis.[22] Findings on MRI suggestive of myelofibrosis include diffuse decrease bone marrow signal intensity.[23] Bone marrow biopsy is the imaging modality of choice for myelofibrosis. A bone marrow biopsy will reveal collagen fibrosis that has replaced the bone marrow. Other diagnostic studies for myelofibrosis include JAK2 mutation analysis testing and bone scan.[21] Red blood cell transfusion, danazol therapy, or thalidomide are recommended for patients who develop anemia. Ruxolitinib, an inhibitor of JAK1 and JAK2, can reduce the splenomegaly and the debilitating symptoms of weight loss, fatigue, and night sweats for patients with JAK2-positive or JAK2-negative primary myelofibrosis, post–essential thrombocythemia myelofibrosis, or post–polycythemia vera myelofibrosis.[24] Hydroxyurea, chemotherapy, radiotherapy, or splenectomy are recommended for patients who develop splenomegaly.[24] Surgery is not the first-line treatment option for patients with myelofibrosis. Splenectomy is usually reserved for patients with massive splenectomy unresponsive to conservative treatment. The only known cure is allogeneic stem cell transplantation, but this approach involves significant risks.[25]
Historical Perspective
Myelofibrosis was first discribed by Gustav Heuck, a German surgeon, in 1879, under the title of 'Two cases of leukemia with peculiar blood and bone marrow findings'.[26]
Classification
Based on the origin, myelofibrosis may be classified into two subtypes: primary and secondary.[27]
Pathophysiology
Myelofibrosis is a clonal neoplastic disorder of hematopoiesis, the formation of blood cellular components. It is one of the myleoproliferative disorders, diseases of the bone marrow in which excess cells are produced. Genes involved in the pathogenesis of myelofibrosis include JAK2, CALR, and MPL.[3]
Causes
Common causes of myelofibrosis include genetic mutations. The genes involved are listed here.[3][28][29]
Differentiating Myelofibrosis from other Diseases
Myelofibrosis must be differentiated from other diseases that cause diffuse bone sclerosis, such as sickle cell disease, hyperthyroidism, sclerosing bone dysplasia, osteoblastic metastases, and Paget's disease.[4][5] Myelofibrosis must be differentiated from other diseases that cause splenomegaly, such as anemia, CML, polycythemia rubra vera, cirrhosis, infections, neoplastic, and lipid storage disorders.[4][6]
Epidemiology and Demographics
The prevalence of myelofibrosis is approximately 1 per 100,000 individuals worldwide. Myelofibrosis is a disease that tends to affect the middle-aged and elderly population. The mean age at diagnosis is 60 years.[7] Males are more commonly affected with myelofibrosis than females. The male to female ratio is approximately 1.5 to 1.[8] Myelofibrosis usually affects individuals of the Ashkenazi Jews race. African American, Latin American, and Asian individuals are less likely to develop myelofibrosis.[9]
Risk Factors
Common risk factors in the development of myelofibrosis may be age, other myeloproliferative disorders, radiation, or industrial chemical exposure.[10]
Natural History, Complications and Prognosis
Myelofibrosis has a very indolent course. If left untreated, myelofibrosis may progress to develop acute myelogenous leukemia, thrombohemorrhagic events, and progressive marrow failure. Common complications of myelofibrosis include infections, bleeding, hepatic failure, heart failure, and gout.[11][12][13][14] Prognosis is generally poor and the median survival for myelofibrosis is 3.5 years to 5.5 years, but patients younger than 55 years have a median survival of 11 years.[13]
Diagnosis
Diagnostic Criteria
According to the World Health Organization (WHO) diagnostic criteria for primary myelofibrosis, polycythemia vera, and essential thrombocythemia, the diagnosis of primary myelofibrosis is made when all three of the following major diagnostic criteria and at least two minor criteria are met.[15][16]
Staging
There is no established system for the staging of myelofibrosis.[13]
Symptoms
Symptoms of myelofibrosis include left upper quadrant abdominal pain, bruising, easy bleeding, pale skin, and frequent infections.[17][18][19]
Physical Examination
Common physical examination findings of myelofibrosis include pallor, petechiae, lymphadenopathy, hepatomegaly, and splenomegaly.[19]
Laboratory Findings
Laboratory findings consistent with the diagnosis of myelofibrosis include decreased red blood cells, normochromic normocytic anemia, tear-drop shaped RBCs, thrombocytopenia, and raised levels of lactate dehydrogenase.[20]
X Ray
X-ray may be helpful in the diagnosis of myelofibrosis. Findings on x-ray suggestive of myelofibrosis include osteosclerosis at different sites of the body, which tends to be diffuse and devoid of architectural distortion.[21]
CT
CT scan may be helpful in the diagnosis of myelofibrosis. Findings on CT scan suggestive of myelofibrosis include diffuse bone sclerosis.[22]
MRI
MRI may be helpful in the diagnosis of myelofibrosis. Findings on MRI suggestive of myelofibrosis include diffuse decrease bone marrow signal intensity.[23]
Bone Marrow Biopsy
Bone marrow biopsy is the imaging modality of choice for myelofibrosis. A bone marrow biopsy will reveal collagen fibrosis that has replaced the bone marrow.
Other Imaging Findings
There are no other imaging findings associated with myelofibrosis.
Other Diagnostic Studies
Other diagnostic studies for myelofibrosis include JAK2 mutation analysis testing and bone scan.[21]
Treatment
Medical Therapy
Red blood cell transfusion, danazol therapy, or thalidomide are recommended for patients who develop anemia. Ruxolitinib, an inhibitor of JAK1 and JAK2, can reduce the splenomegaly and the debilitating symptoms of weight loss, fatigue, and night sweats for patients with JAK2-positive or JAK2-negative primary myelofibrosis, post–essential thrombocythemia myelofibrosis, or post–polycythemia vera myelofibrosis.[24] Hydroxyurea, chemotherapy, radiotherapy, or splenectomy are recommended for patients who develop splenomegaly.[24]
Surgery
Surgery is not the first-line treatment option for patients with myelofibrosis. Splenectomy is usually reserved for patients with massive splenectomy unresponsive to conservative treatment. The only known cure is allogeneic stem cell transplantation, but this approach involves significant risks.[25]
Prevention
There are no primary or secondary preventive measures available for myelofibrosis.[30]
References
- ↑ Shantzer L, Berger K, Pu JJ (April 2017). "Primary myelofibrosis and its targeted therapy". Ann. Hematol. 96 (4): 531–535. doi:10.1007/s00277-016-2785-9. PMID 27539616.
- ↑ Myelofibrosis. Dr Henry Knipe ◉ and Dr Yuranga Weerakkody et al. Radiopaedia 2016. http://radiopaedia.org/articles/myelofibrosis. Accessed on March 7, 2016
- ↑ 3.0 3.1 3.2 Tefferi, A; Lasho, T L; Finke, C M; Knudson, R A; Ketterling, R; Hanson, C H; Maffioli, M; Caramazza, D; Passamonti, F; Pardanani, A (2014). "CALR vs JAK2 vs MPL-mutated or triple-negative myelofibrosis: clinical, cytogenetic and molecular comparisons". Leukemia. 28 (7): 1472–1477. doi:10.1038/leu.2014.3. ISSN 0887-6924.
- ↑ 4.0 4.1 4.2 4.3 Differential diagnosis of myelofibrosis. Dr Henry Knipe and Dr Yuranga Weerakkody et al. Radiopaedia 2016. http://radiopaedia.org/articles/myelofibrosis. Accessed on March 10, 2016
- ↑ 5.0 5.1 Diffuse bony sclerosis: differential diagnosis. Dr Craig Hacking and Dr Yuranga Weerakkody et al. Radiopaedia 2016. http://radiopaedia.org/articles/diffuse-bony-sclerosis-differential-diagnosis. Accessed on March 10, 2016
- ↑ 6.0 6.1 Splenomegaly. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/Italic textarticles/splenomegaly. Accessed on March 11, 2016
- ↑ 7.0 7.1 Epidemiology of myelofibrosis. Dr Henry Knipe and Dr Yuranga Weerakkody et al. Radiopaedia 2016. http://radiopaedia.org/articles/myelofibrosis. Accessed on March 8, 2016
- ↑ 8.0 8.1 Tefferi A, Lasho TL, Jimma T, Finke CM, Gangat N, Vaidya R; et al. (2012). "One thousand patients with primary myelofibrosis: the mayo clinic experience". Mayo Clin Proc. 87 (1): 25–33. doi:10.1016/j.mayocp.2011.11.001. PMC 3538387. PMID 22212965.
- ↑ 9.0 9.1 Causes. The physician's guide to myelofibrosis 2016. http://nordphysicianguides.org/wp-content/uploads/2012/11/NORD_Physician_Guide_to_Myelofibrosis.pdf. Accessed on March 14, 2016
- ↑ 10.0 10.1 Risk factors for myelofibrosis. Mayo clinic 2016. http://www.mayoclinic.org/diseases-conditions/myelofibrosis/basics/risk-factors/con-20027210. Accessed on March 7, 2016
- ↑ 11.0 11.1 Complications of myelofibrosis. US National Library of Medicine 2016. https://www.nlm.nih.gov/medlineplus/ency/article/000531.htm. Accessed on March 7, 2016
- ↑ 12.0 12.1 Kelle, Bayram; Yıldız, Fatih; Paydas, Semra; Bagır, Emine Kılıc; Ergin, Melek; Kozanoglu, Erkan (2015). "Coexistence of hypertrophic osteoarthropathy and myelofibrosis". Revista Brasileira de Reumatologia (English Edition). doi:10.1016/j.rbre.2014.11.004. ISSN 2255-5021.
- ↑ 13.0 13.1 13.2 13.3 13.4 Disease overview of primary myelofibrosis. National cancer institute 2016. http://www.cancer.gov/types/myeloproliferative/hp/chronic-treatment-pdq#section/_9. Accessed on March 10, 2016
- ↑ 14.0 14.1 Complications of primary myelofibrosis. Dr Henry Knipe and Dr Yuranga Weerakkody et al. Radiopaedia 2016. http://radiopaedia.org/articles/myelofibrosis. Accessed on March 10, 2016
- ↑ 15.0 15.1 World Health Organization (WHO) Diagnostic Criteria for Primary Myelofibrosis (PMF), Polycythemia Vera (PV), and Essential Thrombocythemia (ET). MPN Connect 2016. http://www.mpnconnect.com/pdf/who-diagnostic-criteria-myelofibrosis.pdf. Accessed on March 8, 2016
- ↑ 16.0 16.1 Tefferi A, Thiele J, Orazi A, Kvasnicka HM, Barbui T, Hanson CA; et al. (2007). "Proposals and rationale for revision of the World Health Organization diagnostic criteria for polycythemia vera, essential thrombocythemia, and primary myelofibrosis: recommendations from an ad hoc international expert panel". Blood. 110 (4): 1092–7. doi:10.1182/blood-2007-04-083501. PMID 17488875.
- ↑ 17.0 17.1 Symptoms of myelofibrosis. US National Library of Medicine 2016. https://www.nlm.nih.gov/medlineplus/ency/article/000531.htm. Accessed on March 7, 2016
- ↑ 18.0 18.1 Symptoms of idiopathic myelofibrosis. Canadian cancer society 2016. http://www.cancer.ca/en/cancer-information/cancer-type/leukemia/leukemia/idiopathic-myelofibrosis/?region=on. Accessed on March 9, 2016
- ↑ 19.0 19.1 19.2 19.3 Symptoms of primary myelofibrosis include pain below the ribs on the left side and feeling very tired. National cancer institute 2016. http://www.cancer.gov/types/myeloproliferative/patient/chronic-treatment-pdq#section/_234. Accessed on March 10, 2016
- ↑ 20.0 20.1 Diagnosis of idiopathic myelofibrosis. Canadian cancer society 2016. http://www.cancer.ca/en/cancer-information/cancer-type/leukemia/leukemia/idiopathic-myelofibrosis/?region=on. Accessed on March 9, 2016
- ↑ 21.0 21.1 21.2 21.3 Radiographic features of primary myelofibrosis. Dr Henry Knipe and Dr Yuranga Weerakkody et al. Radiopaedia 2016. http://radiopaedia.org/articles/myelofibrosis. Accessed on March 10, 2016
- ↑ 22.0 22.1 Radiographic features of myelofibrosis. Radswiki. Radiopaedia 2016. http://radiopaedia.org/cases/myelofibrosis. Accessed on March 14, 2016
- ↑ 23.0 23.1 Radiographic features of myelofibrosis. Radswiki. Radiopaedia 2016. http://radiopaedia.org/cases/myelofibrosis-1. Accessed on March 14, 2016
- ↑ 24.0 24.1 24.2 24.3 Treatment overview of primary myelofibrosis. National cancer institute 2016. http://www.cancer.gov/types/myeloproliferative/hp/chronic-treatment-pdq#section/_9. Accessed on March 10, 2016
- ↑ 25.0 25.1 Cervantes F (2005). "Modern management of myelofibrosis". Br. J. Haematol. 128 (5): 583–92. doi:10.1111/j.1365-2141.2004.05301.x. PMID 15725078. Unknown parameter
|month=ignored (help) - ↑ Tefferi, A (2007). "The history of myeloproliferative disorders: before and after Dameshek". Leukemia. 22 (1): 3–13. doi:10.1038/sj.leu.2404946. ISSN 0887-6924.
- ↑ Classification of myelofibrosis. Dr Henry Knipe and Dr Yuranga Weerakkody et al. Radiopaedia 2016. http://radiopaedia.org/articles/myelofibrosis. Accessed on March 14, 2016
- ↑ Baxter EJ, Scott LM, Campbell PJ; et al. (2005). "Acquired mutation of the tyrosine kinase JAK2 in human myeloproliferative disorders". Lancet. 365 (9464): 1054–61. doi:10.1016/S0140-6736(05)71142-9. PMID 15781101.
- ↑ Pikman Y, Lee BH, Mercher T; et al. (2006). "MPLW515L is a novel somatic activating mutation in myelofibrosis with myeloid metaplasia". PLoS Med. 3 (7): e270. doi:10.1371/journal.pmed.0030270. PMC 1502153. PMID 16834459. Unknown parameter
|month=ignored (help) - ↑ Prevention of myelofibrosis. US National Library of Medicine 2016. https://www.nlm.nih.gov/medlineplus/ency/article/000531.htm. Accessed on March 7, 2016