About these slides SPEC Short Presentation in Emerging Concepts
Provided by the CAP as an aid to pathologists to facilitate discussion on the topic Content has been reviewed by experts at the CAP, but does not necessarily reflect the official opinion of the College of American Pathologists. Non-CAP material with identified copyright source may only be copied or distributed under a license (permission) from the copyright holder, or under the doctrine offair use. Version 2.0, rev. 8/18/2014 Short Presentations in Emerging Concepts (SPEC)
Emerging Concepts in the Workup of Polycythemia and Thrombocythemia: JAK2 Short Presentations in Emerging Concepts (SPEC) Clinical Question HGB over 18.5 in or 16.5 in ? Platelets over 1 million? Are the hematologic abnormalities reactive or the result of an underlying neoplastic process? JAK-STAT Pathway Cell signaling pathway
Allows extracellular chemicals to effect nuclear DNA expression Erythropoietin signals through the JAK-STAT pathway. JAK2 In Spring 2005, four separate groupsindependently published discovery of a pointmutation (V617F) in the JAK2 gene of patientswith the PV and ET Subsequent studies have identified JAK2mutations as key molecular events in developmentof the myeloproliferative neoplasms (MPNs) Incidence of JAK2 Mutation in MPNs Polycythemia vera (PV) 99% Essential thrombocythemia (ET) 60% Primary myelofibrosis (PMF) 40% Chronic myelogenous leukemia (CML) 18.5 g/dL in men, 16.5 g/dL in women or other evidence of increased red cell volume.* Presence of JAK2V617F or other functionally similar mutation such as JAK2 exon 12 mutation. Minor criteria Bone marrow biopsy showing hypercellularity for age with trilineage growth (panmyelosis) with prominent erythroid, granulocytic, and megakaryocytic proliferation. Serum erythropoietin level below the reference range for normal. Endogenous erythroid colony formation in vitro. Reference: Thiele J, Kvasnicka HM. The 2008 WHO diagnostic criteria for polycythemia vera, essential thrombocythemia, and primary myelofibrosis. Curr Hematol Malig Rep Jan;4(1):33-40. *Hemoglobin or hematocrit > 99th percentile of method-specific reference range for age, sex, and altitude of residence; or hemo- globin > 17 g/dL in men, 15 g/dL in women if associated with a documented and sustained increase of at least 2 g/dL from an individuals baseline value that cannot be attributed to correction of iron deficiency; or elevated red cell mass > 25% above mean normal predicted value. PV Dx Algorithm *Clinical clues for PV include splenomegaly, thrombosis, aquagenic pruritus, and erythromelalgia. Laboratory clues for PV include thrombocytosis, leukocytosis, and increased leukocyte alkaline phosphatase score. Janus kinase 2 (JAK2) screening is to detect the V617F mutation that occurs in most patients with PV. Reference: Tefferi A, Barbui T. bcr/abl-negative, classic myeloproliferative disorders: diagnosis and treatment. Mayo Clin Proc Sep;80(9): Review. Reprinted from Mayo Clin Proc., 80, Tefferi, A and Barbui, T, bcr/abl-negative, classic myeloproliferative disorders: diagnosis and treatment, , Copyright 2005, with permission from Elsevier. Essential thrombocythemia: WHO 2008
Diagnosis requires meeting all four criteria. Sustained* platelet count 450 109/L. Bone marrow biopsy specimen showing proliferation mainly of the megakaryocytic lineage with increased numbers of enlarged, mature megakaryocytes. No signi- ficant increase or left-shift of neutrophil granulopoiesis or erythropoiesis. Not meeting WHO criteria for polycythemia vera, primary myelofibrosis, BCR-ABL1positive chronic myelogenous leukemia, or myelodysplastic syndrome or other myeloid neoplasms. Demonstration of JAK2V617F or other clonal marker, or in the absence of JAK2V617F, no evidence for reactive thrombocytosis.** Reference: Thiele J, Kvasnicka HM. The 2008 WHO diagnostic criteria for polycythemia vera, essential thrombocythemia, and primary myelofibrosis. Curr Hematol Malig Rep Jan;4(1):33-40. *Sustained during the workup process. Requires the failure of iron replacement therapy to increase hemoglobin level to the polycythemia vera range in the presence of decreased serum ferritin. Exclusion of polycythemia vera is based on hemoglobin and hematocrit levels, and red cell mass measure- ment is not required. Requires the absence of relevant reticulin fibrosis, collagen fibrosis, peripheral blood leukoerythroblastosis, or markedly hypercellular marrow accompanied by megakaryocyte morphology that is typical for primary myelofibrosis (small to large megakaryocytes with an aberrant nuclear/cytoplasmic ratio and hyperchromatic, bulbous, or irregularly folded nuclei and dense clustering). Requires the absence of BCR-ABL1. Requires the absence of dyserythropoiesis and dysgranulopoiesis. **Causes of reactive thrombocytosis include iron deficiency, splenectomy, surgery, infection, inflammation, connective tissue disease, metastatic cancer, and lymphoproliferative disorders. However, the presence of a condition associated with reactive thrombocytosis does not exclude the possibility of essential thrombocythemia if the first three criteria are met. ET DiagnosticAlgorithm
Reference: Tefferi A, Barbui T. bcr/abl-negative, classic myeloproliferative disorders: diagnosis and treatment. Mayo Clin Proc Sep;80(9): Review. Reprinted from Mayo Clin Proc., 80, Tefferi, A and Barbui, T, bcr/abl-negative, classic myeloproliferative disorders: diagnosis and treatment, , Copyright 2005, with permission from Elsevier. *In addition to clinical history, laboratory tests that are helpful in distinguishing reactive thrombocytosis from ET include serum ferritin, peripheral blood smear, and C-reactive protein. JAK2 Testing JAK2 V617F Detection JAK2 Exon 12 Mutation Analaysis
Performed on peripheral blood or bone marrow Highly sensitive and specific assays Should be performed in CAP Accredited lab JAK2 Exon 12 Mutation Analaysis Used when suspect PV but V617F not detected Quantification of JAK2? diagnosis clinical/hematologic/
Detection is sufficient. Quantification not necessary diagnosis clinical/hematologic/ prognostic correlates Controversial Response to therapy Utility not well defined clinically monitoring CALR Mutations Second most frequent mutation after JAK2
CALR found in endoplasmic reticulin: protein folding, calcium homeostasis CALR mutations mutually exclusive with JAK2 and MPL Found in 73% of ET and MF cases that are JAK2 neg and MPL neg CALR not reported in PV Can distinguish ET from PV and MF Presence of CALR mutation associated with better outcomes (longer survival, less thrombosis) Nangalia J, Massie CE, Baxter EJ, et al. Somatic CALR mutations in myeloproliferative neoplasms with nonmutated JAK2. N Engl J Med. 2013; 369: Klampfl T, Gisslinger H, Harutyunyan AS, et al. Somatic mutations of calreticulin in myeloproliferative neoplasms. N Engl J Med. 2013; 369: Selected Resources Nangalia J, Massie CE, Baxter EJ, et al. Somatic CALR mutations in myeloproliferative neoplasms with nonmutated JAK2. N Engl J Med. 2013; 369: Klampfl T, Gisslinger H, Harutyunyan AS, et al. Somatic mutations of calreticulin in myeloproliferative neoplasms. N Engl J Med. 2013; 369: Cross NC. Genetic and epigenetic complexity in myeloproliferative neoplasms. Hematology Am Soc Hematol Educ Program. 2011;2011: Schmidt AE, Pathology Consultation on Myeloproliferative Neoplasms. Oh ST; for the Education Committee of the Academy of Clinical Laboratory Physicians and Scientists. Am J Clin Pathol Jul;138(1): Tefferi A. JAK inhibitors for myeloproliferative neoplasms: clarifying facts from myths. Blood Mar 22;119(12): Epub 2012 Jan 25. Additional Free Resource for CAP MembersNOTE: please remove this page before presenting.
CAP Member Exclusive: CAP Pathology Resource Guides Focused on a specific hot-topic technology, these comprehensive guides highlights current resources, select journal articles, as well as CAP and non-CAP educational opportunities. And dont miss the Insights From Early Adopters section in each guide to gain perspective from pioneering colleagues. AVAILABLE NOW: Molecular Pathology (single gene test, small panel) Genomic Analysis (large panel, exome, genome) Learn more: go to cap.org and type Pathology Resource Guides in the search field located at the top of your screen. An outstanding overview of basic materials, including the technology and links to a number of individuals and centers that can assist. Extremely well done, of high practical and educational value.