Myelofibrosis Classification and external resources ICD-10 C94.5, D47.1 ICD-9 289.83 ICD-O: 9932, M9961/3 OMIM 254450 DiseasesDB 8616 MeSH D055728
Myelofibrosis, also known as myeloid metaplasia, chronic idiopathic myelofibrosis, osteomyelofibrosis and primary myelofibrosis is a disorder of the bone marrow. It is currently classified as a myeloproliferative disease in which the proliferation of an abnormal type of bone marrow stem cell results in fibrosis, or the replacement of the marrow with collagenous connective tissue fibers.
History and terminology
Older terms include "myelofibrosis with myeloid metaplasia" and "agnogenic myeloid metaplasia". The World Health Organization utilizes the name "chronic idiopathic myelofibrosis", while the International Working Group on Myelofibrosis Research and Treatment calls the disease "primary myelofibrosis". Eponyms for the disease are Heuck-Assmann disease or Assmann's Disease, for Herbert Assmann, who published a description under the term "osteosclerosis" in 1907.
Signs and symptoms
- Abdominal fullness related to an enlarged spleen (splenomegaly).
- Bone pain
- Bruising and easy bleeding due to inadequate numbers of platelets
- Increased susceptibility to infection, such as pneumonia or diarrhea
- Pallor and shortness of breath while doing physical work due to anemia
- Because of a high rate of cell turnover, hyperuricemia and gout may also complicate the picture
- Primary myelofibrosis can begin with a blood picture suggestive of Polycythemia Vera or CML
- Most patients have moderate to severe anemia
- Eventually patient develops thrombocytopenia
- The peripheral smear appears markedly abnormal
- Red cell abnormality includes bizarre shapes
- Nucleated erythroid precursors are seen in the peripheral blood
- Immature white cells are also seen and basophils are increased
The principal site of extramedullary hematopoiesis in myeloid metaplasia with primary myelofibrosis is the spleen which is usually markedly enlarged, sometimes weighing as much as 4000 g. As is always true when splenomegaly is massive, multiple subcapsular infarcts are often present. Histologically the spleen contains normoblast, granulocyte precursor and megakaryocytes, which are often prominent in terms of their numbers and bizarre morphology. Sometimes disproportional activity of any one of the three major cell lines is seen.
The liver is often moderately enlarged, with foci of extramedullary hematopoiesis. Microscopically, lymph nodes also contain foci of hematopoiesis, but these are insufficient to cause enlargement.
The bone marrow in a typical case is hypocellular and diffusely fibrotic. Both early and late in disease, megakaryocytes are often prominent and are usually dysplastic.
The bone marrow is replaced by collagen fibrosis, impairing the patient's ability to generate new blood cells resulting in a progressive pancytopenia. It is usually reactive following other myeloproliferative disorders, such as polycythemia rubra vera or essential thrombocytosis. Extramedullary haematopoeisis occurs as the haemopoetic cells migrate away from the bone marrow, to the liver and spleen. Patients often have hepatosplenomegaly and poikilocytosis.
In primary myelofibrosis, a progressive scarring (fibrosis) of the bone marrow occurs. As a result, blood forms in sites other than the bone marrow, such as the liver and spleen. This causes an enlargement of these organs. The cause and risk factors are unknown. It commonly occurs in the spent phase of Polycythemia rubra vera, possibly in response to the medication hydroxyurea poisoning the marrow and blood.
The only known cure is allogeneic stem cell transplantation, but this approach involves significant risks. Other treatment options are largely supportive, and do not alter the course. These options may include regular folic acid, allopurinol or blood transfusions. Dexamethasone, alpha-interferon and hydroxycarbamide may play a role.
Frequent blood transfusions may also be required. If the patient is diabetic and is taking sulfonylureas medication this should be stopped periodically to rule out drug-induced thrombocytopenia.
In November 2011, the FDA approved Ruxolitinib as a treatment for Myelofibrosis. Ruxolitinib is a twice daily drug which serves as an inhibitor of JAK 1 and 2.
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- ^ Narasimhaiah Srinivasaiah, Mohammad K Zia and Vummiti Muralikrishnan, Peritonitis in myelofibrosis: a cautionary tale, Hepatobiliary & Pancreatic Diseases International 2010; 9: 651-653.
- ^ a b Tefferi, A., Siragusa, S., et al, Transfusion-dependency at presentation and its acquisition in the first year of diagnosis are both equally detrimental for survival in primary myelofibrosis—prognostic relevance is independent of IPSS or karyotype, American Journal of Hematology, 85(1): 14–17 (2010). doi: 10.1002/ajh.21574.
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- ^ Spivak, Jerry L1; Hasselbalch, Hans, Hydroxycarbamide: a user's guide for chronic myeloproliferative disorders, Expert Review of Anticancer Therapy, Vol. 11(3), Mar. 2011, pp. 403-414.
- ^ a b Lacy, M. and Tefferi, A., Pomalidomide therapy for multiple myeloma and myelofibrosis: an update, Leukemia & Lymphoma, April 2011, 52(4), pp. 560-566, (doi:10.3109/10428194.2011.552139).
- ^ Primary Myelofibrosis, Merck.
Myeloid hematological malignancy/leukemia histology (ICD-O 9590–9989, C81–C96, 200–208) CFU-GM/
and other granulocytesCFU-GMOtherCFU-BasoCFU-Eos
MEPCFU-MegCFU-E CFU-Mast Multiple/unknown
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Look at other dictionaries:
myelofibrosis — n. (Med.) Fibrosis of the bone marrow. [WordNet 1.5] … The Collaborative International Dictionary of English
Myelofibrosis — Fibrosis (spontaneous scarring) of the bone marrow. This can be associated with a variety of diseases, primarily myeloproliferative (pre leukemic) disorders. Sometimes used interchangeably with agnogenic myeloid metaplasia. Myelofibrosis is… … Medical dictionary
myelofibrosis — noun Etymology: New Latin Date: 1947 an anemic condition in which bone marrow becomes fibrotic and the liver and spleen usually exhibit a development of blood cell precursors • myelofibrotic adjective … New Collegiate Dictionary
myelofibrosis — /muy euh loh fuy broh sis/, n. Pathol. the replacement of bone marrow by fibrous tissue, characteristic of leukemia and certain other diseases. [1945 50; MYELO + FIBROSIS] * * * … Universalium
myelofibrosis — noun A myeloproliferative disorder of the bone marrow, in which the marrow undergoes fibrosis … Wiktionary
myelofibrosis — my·elo·fibrosis … English syllables
myelofibrosis — n. a chronic but progressive disease characterized by fibrosis of the bone marrow, which leads to anaemia and the presence of immature red and white blood cells in the circulation. Other features include enlargement of the spleen and the presence … The new mediacal dictionary
myelofibrosis — my•e•lo•fi•bro•sis [[t]ˌmaɪ ə loʊ faɪˈbroʊ sɪs[/t]] n. pat the replacement of bone marrow by fibrous tissue, characteristic of leukemia and certain other diseases • Etymology: 1945–50 … From formal English to slang
myelofibrosis — A disorder in which the bone marrow is replaced by fibrous tissue … English dictionary of cancer terms
myelofibrosis — noun fibrosis of the bone marrow (Freq. 1) • Hypernyms: ↑fibrosis * * * /muy euh loh fuy broh sis/, n. Pathol. the replacement of bone marrow by fibrous tissue, characteristic of leukemia and certain other diseases. [1945 50; MYELO + FIBROSIS] … Useful english dictionary