Polycythemia vera classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: ;Mohamad Alkateb, MBBCh [2] Shyam Patel [3]
Overview
Polycythemia vera is a subtype of myeloproliferative neoplasm. Myeloproliferative neoplasm may be classified according to the World Health Organization into eight subtypes: chronic myelogenous leukemia, chronic neutrophilic leukemia, polycythemia vera, primary myelofibrosis, essential thrombocythemia, chronic eosinophilic leukemia, mastocytosis, and myeloproliferative neoplasms, unclassifiable. The classification of polycythemia is subdivided into primary polycythemia (which is a clonal process caused by the JAK2 mutation) and secondary polycythemia (which is a reactive process due to a state of chronic hypoxia). There are numerous causes of secondary polycythemia, and most of these causes are cardiopulmonary in origin.
Classification
Classification of myeloproliferative neoplasms
Polycythemia vera is a subtype of myeloproliferative neoplasm. Myeloproliferative neoplasm may be classified according to the World Health Organization into eight subtypes:[1][2]
- Polycythemia vera: This is a condition of elevated hemoglobin and red blood cell mass caused by the JAK2 mutation.
- Essential thrombocythemia: This is a condition of elevated platelet count caused by a variety of mutations, such as JAK2, CALR, or MPL.[3] These mutations are mutually exclusive. The disease is characterized by increased propensity for thrombotic events. This condition can progress to myelofibrosis, which carries a poor prognosis.[3]
- Chronic myelogenous leukemia, BCR-ABL1–positive: This condition is a common cause of chronic leukemia. The peripheral blood of patients with chronic myelogenous leukemia commonly shows elevation of white blood cell precursors at all stages of maturation, including metamyelocytes, and band cells.[4] Treatment involves oral tyrosine kinase inhibitors such as imatinib, dasatinib, bosutinib, nilotinib, or ponatinib.[4]
- Chronic myelogenous leukemia, BCR-ABL1–negative (atypical CML): This a condition that carries a high risk for transformation into acute myeloid leukemia. It is frequently underdiagnosed since the BCR-Abl translocation is not found. Treatment considerations include allogeneic stem cell transplantation.[5]
- Chronic neutrophilic leukemia: This is a condition characterized by elevation of neutrophil count and is commonly caused by a mutation in the colony-stimulating factor 3R (CSF3R) gene.
- Primary myelofibrosis: This is a highly lethal condition in which the bone marrow is replaced by reticulin fibrosis, resulting in ineffective erythropoiesis. The etiology of this disease is abnormal megakaryocyte proliferation and excess production of transforming growth factor-beta (TGF-beta), which stimulates collagen deposition and fibrosis.[6]
- Chronic eosinophilic leukemia, not otherwise specified: This condition is characterized by elevation of the eosinophil count to greater than 1,500/mcl. In hypereosinophilic syndrome, there is end-organ involvement (especially hepatic and cardiac) due to eosinophil infiltration into organs. The most common etiology is the FIP1L1-PDGFRalpha rearrangement in chromosome 4, which in turn is due to deletion of the intervening CHIC2 locus. It commonly affects males.[7]
- Mastocytosis: This condition is caused by mast cell proliferation and results in symptoms of coughing, wheezing, gastrointestinal upset, anaphylaxis, and diarrhea.[8] Patients typically have high levels of histamine (a peptide released by mast cells). Treatment usually involves imatinib. In 2016, it was discovered that the tyrosine kinase inhibitor midostaurin could effectively treat mastocytosis, including patients who harbor the D816V mutation for which imatinib is ineffective.[8]
- Myeloproliferative neoplasms, unclassifiable
There are no subcategories within polycythemia vera.
Classification of polycythemia
Polycythemia vera is a subcategory of polycythemia in general. Classification of polycythemia in general includes primary polycythemia and secondary polycythemia. Secondary polycythemia is due to chronic hypoxia which results in compensatory increase in erythrocyte production. Secondary polycythemia is therefore characterized by a reactive increase in erythrocyte production, rather than clonal proliferation of erythrocytes.
- Primary polycythemia (polycythemia vera)
- Secondary polycythemia
- Congestive heart failure: This condition is defined as the inability of the circulatory system to meet the metabolic demands of exercising tissues.
- Chronic obstructive pulmonary disease: This is a group of disorders including chronic bronchitis and emphysema.
- Interstitial lung disease: This condition is due to destruction of the pulmonary parenchyma, resulting in fibrosis and scarring of the lung tissue. There are a variety of causes.
- Smoking: Cigarette smoking can cause a state of chronic hypoxia.
- Obstructive sleep apnea: This condition is due to physical impediment of the airways, resulting temporary cessation of breathing at night. This causes a state of chronic hypoxia.
- High altitude residence: Elevated heights carry low oxygen content.
- Erythropoietin-secreting tumors
- Renal cell carcinoma: This is a malignancy of the kidney epithelial cells that sometimes produces the hormone erythropoietin.
- Hepatocellular carcinoma: This is a malignancy of the liver epithelial cells that sometimes produces the hormone erythropoietin.
References
- ↑ Vardiman JW, Thiele J, Arber DA, Brunning RD, Borowitz MJ, Porwit A; et al. (2009). "The 2008 revision of the World Health Organization (WHO) classification of myeloid neoplasms and acute leukemia: rationale and important changes". Blood. 114 (5): 937–51. doi:10.1182/blood-2009-03-209262. PMID 19357394.
- ↑ Valent P, Horny HP, Escribano L, Longley BJ, Li CY, Schwartz LB; et al. (2001). "Diagnostic criteria and classification of mastocytosis: a consensus proposal". Leuk Res. 25 (7): 603–25. PMID 11377686.
- ↑ 3.0 3.1 Birgegård G (2015). "Advances and challenges in the management of essential thrombocythemia". Ther Adv Hematol. 6 (3): 142–56. doi:10.1177/2040620715580068. PMC 4480522. PMID 26137205.
- ↑ 4.0 4.1 Hayashi Y, Hirai H, Kamio N, Yao H, Yoshioka S, Miura Y; et al. (2013). "C/EBPβ promotes BCR-ABL-mediated myeloid expansion and leukemic stem cell exhaustion". Leukemia. 27 (3): 619–28. doi:10.1038/leu.2012.258. PMC 4506742. PMID 22948537.
- ↑ Gotlib J (2017). "How I treat atypical chronic myeloid leukemia". Blood. 129 (7): 838–845. doi:10.1182/blood-2016-08-693630. PMID 27899359.
- ↑ Desterke C, Martinaud C, Ruzehaji N, Le Bousse-Kerdilès MC (2015). "Inflammation as a Keystone of Bone Marrow Stroma Alterations in Primary Myelofibrosis". Mediators Inflamm. 2015: 415024. doi:10.1155/2015/415024. PMC 4660030. PMID 26640324.
- ↑ Legrand F, Renneville A, Macintyre E, Mastrilli S, Ackermann F, Cayuela JM; et al. (2013). "The Spectrum of FIP1L1-PDGFRA-Associated Chronic Eosinophilic Leukemia: New Insights Based on a Survey of 44 Cases". Medicine (Baltimore). doi:10.1097/MD.0b013e3182a71eba. PMC 4553979. PMID 23982058.
- ↑ 8.0 8.1 Valent P, Akin C, Hartmann K, Nilsson G, Reiter A, Hermine O; et al. (2017). "Advances in the Classification and Treatment of Mastocytosis: Current Status and Outlook toward the Future". Cancer Res. 77 (6): 1261–1270. doi:10.1158/0008-5472.CAN-16-2234. PMC 5354959. PMID 28254862.