Current diagnostic criteria for the chronic myeloproliferative disorders (MPD) essential thrombocythemia (ET), polycythemia vera (PV) and chronic idiopathic myelofibrosis (CIMF)

Evolution of WHO diagnostic criteria in "Classical Myeloproliferative Neoplasms" compared with the International Consensus Classification

A lively discussion persists regarding the diagnostic criteria for essential thrombocythemia (ET), primary myelofibrosis (PMF) and polycythemia vera (PV), particularly in relation to early/pre-fibrotic myelofibrosis (pre-PMF), a disease entity initially introduced in 2001 by the 3rd edition of the World Health Organization (WHO) classification. The definition and criteria used to diagnose pre-PMF have been progressively modified over time. The most update definition of pre-PMF can be found in the International Consensus Classification (ICC) published in 2022. An updated largely similar definition is also incorporated in the recently published 5th edition of WHO classification (2024). Diagnostic criteria for ET have undergone changes up to 2016/17 for the revised 4th edition of the WHO. In particular the threshold value for platelets were lowered and the important discrimination between "true" and "false" ET (in reality pre-PMF) been widely acknowledged. To avoid misdiagnose in early phase PV, the criteria for gender-adjusted thresholds for hemoglobin/ hematocrit have been lowered and the identification of an appropriate bone marrow (BM) morphology was upgraded as a major diagnostic criterion. Given the prominent role of morphology in MPN-related diagnostic algorithms, the diagnostic adequacy of the BM biopsy (sample procurement and proper laboratory handling) as emphasized in former WHO editions and in the ICC, was not addressed by the WHO 5th. The essential role of genetic markers is recognized by both classifications. A comparison between the revised 4th edition WHO classification and the ICC versus the WHO 5th reveals no significant differences, with the exception of the occurrence of leukoerythroblastosis in pre-PMF considered by the latter as one of the minor diagnostic criteria which seems unwarranted. In contrast to the revised 4th edition, the majority of the microscopic images used for the WHO 5th due to their low magnification and poor technique, do not highlight the diagnosis differences among these entities.

The utility of testing erythropoietin level in polycythemia diagnosis

OBJECTIVES

Polycythemia vera (PV) is classically thought to be associated with low erythropoietin (EPO) levels. Here, we present a review of the utility of using EPO levels in diagnosing polycythemia.

METHODS

We conducted a systematic literature review of the Medline data through Pubmed and Google Scholar. We included the articles which described confirmed PV associated with elevated EPO level. Our search strategy included the following terms in Pubmed (((polycythemia vera[MeSH Terms]) OR (jak2 protein tyrosine kinase[MeSH Terms])) OR (Myeloproliferative Disorders[MeSH Terms])) AND (Erythropoietin[MeSH Terms]), and 'polycythemia vera with erythropoietin' in Google Scholar.

RESULTS

Our research yielded four cases of PV with elevated EPO levels. The most common symptom was a headache. Thrombotic phenomena happened in a single case in the form of Budd-Chiari syndrome. The mean Hb level was 20.2 gm/dl, and the EPO level was 213 mlU/mL.

DISCUSSION

Although PV is usually associated with low EPO levels, high levels do not exclude this diagnosis. Workup should include testing for JAK2 mutation and bone marrow biopsy in the presence of suggestive signs and symptoms. Novel biomarkers are also being proposed to aid in the diagnosis.

CONCLUSION

Although elevated EPO levels suggest secondary causes of polycythemia, cases where elevated EPO levels were associated with an underlying PV are reported in the literature, and we have summarized a review of them. Workup for polycythemia should include JAK2 mutation testing if signs and symptoms suggest PV even if EPO is elevated.

CD177 Expression and Inflammation Grade in Helicobacter pylori-Infected Wild-Type and CD177-/- C57BL/6 Mice

This study was undertaken to further investigate the CD177 expression in Helicobacter pylori- (Hp-) infected wild-type and CD177^-/- C57BL/6 mice, which may be helpful to elucidate the relationship between CD177 and Hp-related gastritis. 20 WT mice were randomly assigned into the Hpss1 WT group (n = 10) and Hp49503 WT group (n = 10); 20 KO mice were randomly assigned into the Hpss1 KO group (n = 10) and Hp49503 KO group (n = 10). The remaining mice served as controls. Mice in the HpSS1 groups and Hp49503 groups were independently infected with corresponding strains. Results showed that the Hp colonization score was related to the grade of mucosal inflammation (P < 0.05). The inflammation grade was comparable between the HpSS1 group and Hp49503 group as well as between the WT group and KO group. In addition, the Hp colonization score was related to the CD177 expression score (P < 0.05). The CD177 expression in the Hp colonization group was higher than that in the non-Hp colonization group (P < 0.05). CD177 expression was positively related to the inflammation grade (P < 0.01). In conclusion, CD177 expression was similar between HP49503- and HPss1-infected WT C57BL/6 mice, and CD177 expression was undetectable in CD177^-/- mice. CD177 expression in the gastric mucosa increases with the elevation of inflammation grade. In Hp-infected mice, the inflammation grade had no relationship with the type of Hp strain and the CD177 expression, but the mucosal inflammation score in Hp-infected mice was higher than that in non-Hp infected mice.

Long-term outcomes following percutaneous hepatic vein recanalization for Budd-Chiari syndrome

BACKGROUND & AIMS

A proportion of patients with Budd-Chiari Syndrome (BCS) associated with stenosis or short occlusion of the hepatic vein (HV) or upper inferior vena cava (IVC) can be treated with recanalization by percutaneous venoplasty ± HV stent insertion. We studied the long-term outcomes of this approach.

METHODS

Single-centre retrospective analysis of patients referred for radiological assessment ± intervention over a 27-year period. Of 155 BCS patients, 63 patients who underwent venoplasty were studied and compared to a previously reported series treated by TIPSS (n = 59).

RESULTS

Patients treated with HV interventions (32 venoplasty alone, 31 endovascular stents): mean age, 34.9 ± 10.9; M:F ratio 27:36; median follow-up, 113.0 months; 62% of patients had ≥1 haematological risk factor. Technical success was 100%, with symptom resolution in 73%. Cumulative secondary patency at 1, 5, 10 years was 92%, 79%, 79% and 69%, 69%, 64% in the stenting and venoplasty groups respectively. Where long-term patency was not achieved, 10 patients required TIPSS, and 8 underwent surgery. Actuarial survival at 1, 5, 10 years was 97%, 89% and 85%. When compared to TIPSS, HV interventions resulted in similar patency and survival rates but significantly lower procedural complications (9.5% vs 27.1%) and hepatic encephalopathy (0% vs 18%). Patient age predicted survival following multivariate analysis.

CONCLUSIONS

Our data support the stepwise approach to management of BCS, with very good outcomes from venoplasty combined with stenting when required. TIPSS should only be offered where HV interventions are not feasible or unsuccessful.

A Case of Metanephric Adenoma and Acute Myocardial Infarction

Metanephric adenoma (MA) is a rare neoplasm that acounts for 0.2% of adult renal neoplasms. MAs are typically discover incidentally during detailed examinations for nonspecific symptoms such as abdominal or flank pain, hematuria, fever and palpable abdominal mass. Additionally, polycythemia has occasionally been reported as well. Herein we describe a case of metanephric adenoma which was an incidental finding in the course of a clinical autopsy in a patient with complete AV block and polycythemia. Histologically, the tumor was composed of small and uniform tubular structures reminiscent of renal tubuli, without signs of cellular atypia and pleomorphism. Such tumor histomorphology was consistent with the diagnosis of metanephric adenoma. Thrombosis is a common complication of polycythemia that often causes death. Polycythemia with an increasing number of blood cells causes hyperviscosity and, in 20-40% of cases, lethal thrombosis or hemorrhage. Hyperviscosity and coronary artery disease in our patient caused acute myocardial infarction with the subsequent rupture of posterior left ventricle wall and hemopericardium.

European vs 2015-World Health Organization clinical molecular and pathological classification of myeloproliferative neoplasms

The BCR/ABL fusion gene or the Ph¹-chromosome in the t(9;22)(q34;q11) exerts a high tyrokinase acticity, which is the cause of chronic myeloid leukemia (CML). The 1990 Hannover Bone Marrow Classification separated CML from the myeloproliferative disorders essential thrombocythemia (ET), polycythemia vera (PV) and chronic megakaryocytic granulocytic myeloproliferation (CMGM). The 2006-2008 European Clinical Molecular and Pathological (ECMP) criteria discovered 3 variants of thrombocythemia: ET with features of PV (prodromal PV), “true” ET and ET associated with CMGM. The 2008 World Health Organization (WHO)-ECMP and 2014 WHO-CMP classifications defined three phenotypes of JAK2^V617F mutated ET: normocellular ET (WHO-ET), hypercelluar ET due to increased erythropoiesis (prodromal PV) and ET with hypercellular megakaryocytic-granulocytic myeloproliferation. The JAK2^V617F mutation load in heterozygous WHO-ET is low and associated with normal life expectance. The hetero/homozygous JAK2^V617F mutation load in PV and myelofibrosis is related to myeloproliferative neoplasm (MPN) disease burden in terms of symptomatic splenomegaly, constitutional symptoms, bone marrow hypercellularity and myelofibrosis. JAK2 exon 12 mutated MPN presents as idiopathic eryhrocythemia and early stage PV. According to 2014 WHO-CMP criteria JAK2 wild type MPL⁵¹⁵ mutated ET is the second distinct thrombocythemia featured by clustered giant megakaryocytes with hyperlobulated stag-horn-like nuclei, in a normocellular bone marrow consistent with the diagnosis of “true” ET. JAK2/MPL wild type, calreticulin mutated hypercellular ET appears to be the third distinct thrombocythemia characterized by clustered larged immature dysmorphic megakaryocytes and bulky (bulbous) hyperchromatic nuclei consistent with CMGM or primary megakaryocytic granulocytic myeloproliferation.

Characterization of a novel mouse model with genetic deletion of CD177

Neutrophils play an essential role in the innate immune response to infection. Neutrophils migrate from the vasculature into the tissue in response to infection. Recently, a neutrophil cell surface receptor, CD177, was shown to help mediate neutrophil migration across the endothelium through interactions with PECAM1. We examined a publicly available gene array dataset of CD177 expression from human neutrophils following pulmonary endotoxin instillation. Among all 22,214 genes examined, CD177 mRNA was the most upregulated following endotoxin exposure. The high level of CD177 expression is also maintained in airspace neutrophils, suggesting a potential involvement of CD177 in neutrophil infiltration under infectious diseases. To determine the role of CD177 in neutrophils in vivo, we constructed a CD177-genetic knockout mouse model. The mice with homozygous deletion of CD177 have no discernible phenotype and no significant change in immune cells, other than decreased neutrophil counts in peripheral blood. We examined the role of CD177 in neutrophil accumulation using a skin infection model with Staphylococcus aureus. CD177 deletion reduced neutrophil counts in inflammatory skin caused by S. aureus. Mechanistically we found that CD177 deletion in mouse neutrophils has no significant impact in CXCL1/KC- or fMLP-induced migration, but led to significant cell death. Herein we established a novel genetic mouse model to study the role of CD177 and found that CD177 plays an important role in neutrophils.

Changing concepts of diagnostic criteria of myeloproliferative disorders and the molecular etiology and classification of myeloproliferative neoplasms: from Dameshek 1950 to Vainchenker 2005 and beyond

The Polycythemia Vera Study Group (PVSG) and WHO classifications distinguished the Philadelphia (Ph(1)) chromosome-positive chronic myeloid leukemia from the Ph(1)-negative myeloproliferative neoplasms (MPN) essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (MF) or primary megakaryocytic granulocytic myeloproliferation (PMGM). Half of PVSG/WHO-defined ET patients show low serum erythropoietin levels and carry the JAK2(V617F) mutation, indicating prodromal PV. The positive predictive value of a JAK2(V617F) PCR test is 95% for the diagnosis of PV, and about 50% for ET and MF. The WHO-defined JAK2(V617F)-positive ET comprises three ET phenotypes at clinical and bone marrow level when the integrated WHO and European Clinical, Molecular and Pathological (ECMP) criteria are applied: normocellular ET (WHO-ET), hypercellular ET due to increased erythropoiesis (prodromal PV) and hypercellular ET associated with megakaryocytic granulocytic myeloproliferation (EMGM). Four main molecular types of clonal MPN can be distinguished: JAK2(V617F)-positive ET and PV; JAK2 wild-type ET carrying the MPL(515); mutations in the calreticulin (CALR) gene in JAK2/MPL wild-type ET and MF, and a small proportion of JAK2/MPL/CALR wild-type ET and MF patients. The JAK2(V617F) mutation load is low in heterozygous normocellular WHO-ET. The JAK2(V617F) mutation load in hetero-/homozygous PV and EMGM is clearly related to MPN disease burden in terms of splenomegaly, constitutional symptoms and fibrosis. The JAK2 wild-type ET carrying the MPL(515) mutation is featured by clustered small and giant megakaryocytes with hyperlobulated stag-horn-like nuclei, in a normocellular bone marrow (WHO-ET), and lacks features of PV. JAK2/MPL wild-type, CALR mutated hypercellular ET associated with PMGM is featured by dense clustered large immature dysmorphic megakaryocytes and bulky (cloud-like) hyperchromatic nuclei, which are never seen in WHO-ECMP-defined JAK2(V617F) mutated ET, EMGM and PV, and neither in JAK2 wild-type ET carrying the MPL(515) mutation. Two thirds of JAK2/MPL wild-type ET and MF patients carry one of the CALR mutations as the cause of the third distinct MPN entity. WHO-ECMP criteria are recommended to diagnose, classify and stage the broad spectrum of MPN of various molecular etiologies.

Multisite evaluation of a monoclonal IMMULITE erythropoietin immunoassay

BACKGROUND

Erythropoietin (EPO) measurements are useful in diagnosing anemias and polycythemias. We conducted a multisite evaluation of a monoclonal IMMULITE® EPO immunoassay.(1) DESIGN AND METHODS: The IMMULITE EPO assay is a solid-phase enzyme-labeled chemiluminescent immunometric assay. Method comparison to the Beckman ACCESS 2 assay using clinically characterized samples and reproducibility studies were conducted at three external independent laboratories. Internal evaluation conducted at Siemens included comparison of IMMULITE® 2000 and IMMULITE® 1000 assays to the ACCESS 2 assay; imprecision; linearity; limit of blank (LoB), limit of detection (LoD), and functional sensitivity; potential interference and cross-reactants; and reference interval determination.

RESULTS

External method comparison gave Deming regression of (IMMULITE 2000)=0.96(ACCESS 2)+2.57IU/L, r=0.98 (n=217). Reproducibility ranged from 6.1% to 16.2%. Internal method comparisons gave Deming regressions of (IMMULITE 2000)=1.09(ACCESS 2)-3.51IU/L, r=0.98 and (IMMULITE 1000)=0.95(ACCESS 2)+0.52IU/L, r=0.95. Total imprecision ranged from 6.4% to 10.3% and linearity was confirmed from 3.5 to 562IU/L. LoB, LoD, and functional sensitivity were 0.5, 1.0, and 1.5IU/L, respectively. The assay was highly specific for EPO. Nonparametric reference interval was 4.3 to 29.0IU/L (n=170).

CONCLUSIONS

The monoclonal IMMULITE EPO assay showed acceptable performance for EPO measurement.

An update on the diagnosis and management of Budd-Chiari syndrome

Budd-Chiari syndrome is a rare disorder caused by hepatic venous outflow obstruction and resulting hepatic dysfunction. Despite a lack of prospective randomized trials, much progress has been made in its management over the last 20 years. The main goals of treatment are to ameliorate hepatic congestion and prevent further thrombosis. The selective use of anticoagulation, vascular stents, transjugular intrahepatic portosystemic stent-shunt and liver transplant has resulted in a significant increase in survival. The diagnosis, initial management and long-term follow-up of patients with Budd-Chiari syndrome is reviewed. The concept of individualization of treatment and a stepwise approach to invasive procedures is also discussed.

Reproducibility of histologic classification in nonfibrotic myeloproliferative neoplasia

Early phases of polycythemia vera, essential thrombocythemia, and primary myelofibrosis (PMF) can be difficult to distinguish by morphologic studies alone because they share many morphologic characteristics. Histologic criteria according to the 2008 World Health Organization (WHO) classification are part of the myeloproliferative neoplasia (MPN) diagnosis. Our aim was to assess the reproducibility of morphologic characteristics and determine their relative importance for histologic diagnoses on selected trephine biopsy sections. For the study, 56 prefibrotic MPN trephine specimens were blindly reviewed by 4 hematopathologists using a scoring list of 16 histologic characteristics mentioned in the WHO classification. Consensus was defined as agreement by 3 of 4 hematopathologists. High degrees of consensus were reached for individual major morphologic features used in the WHO classification, especially for the nuclear features of megakaryocytes (83%). Some of the features correlated positively or negatively with the histologic diagnosis of PMF. Consensus for the histologic classification of MPN was reached in 39 (70%) of 56 cases without knowledge of clinical data. This finding indicates a difference in the relative importance assigned to individual histologic characteristics by different hematopathologists.

Cerebral Venous Thrombosis and Venous Infarction: Case Report of a Rare Initial Presentation of Smoker's Polycythemia

Introduction

Cerebral venous thrombosis is a rare initial presentation of polycythemia. If diagnosed early, treatment can reduce mortality and morbidity significantly. Often it may present with headache as the only complaint, and thus the diagnosis is likely to be missed.

Case Presentation

A medically stable 31-year-old male, a chronic smoker with a ∼17 pack-year history of smoking, was admitted to the emergency room with a 2-week history of gradually worsening, severe, throbbing headache in the occipital region sensitive to light. Initial neurological examination was positive only for some involuntary motor tics of the left leg. Initial laboratory workup showed hemoglobin of 20 g/dl and hematocrit of 56.5%. The carboxyhemoglobin level was normal, but the oxygen dissociation curve was shifted to the left. Further evaluation by MRI and MRA of the brain suggested extensive and complete thrombosis of the superior sagittal sinus, right transverse sinus and right sigmoid sinus with a small venous infarct in the right parafrontal region. Given that the patient first presented with a thrombotic event, workup for primary polycythemia and hypercoagulable disorders was carried out, including JAK2 mutation evaluation, which was negative. This left us with smoking as the only risk factor and possible cause for secondary polycythemia. He improved significantly with phlebotomy and anticoagulation treatment.

Conclusion

This case illustrates a rare but severe complication of secondary polycythemia stressing the importance of being aware of the risk of developing cerebral thrombosis in patients with chronic smoking exposure.

Practical application and clinical impact of the WHO histopathological criteria on bone marrow biopsy for the diagnosis of essential thrombocythemia versus prefibrotic primary myelofibrosis

AIMS

To evaluate the feasibility of the histopathological diagnosis of prefibrotic-early primary myelofibrosis (PM) as described in the World Health Organization (WHO) classification and to evaluate the clinical implications of prefibrotic-early PM in a series of patients previously diagnosed as having essential thrombocythemia (ET) according to the Polycythemia Vera Study Group criteria.

METHODS AND RESULTS

WHO criteria were applied to bone marrow biopsy specimens by two pathologists who then reclassified 127 cases as 102 ET (80.3%), 18 prefibrotic-early PM (14.2%) and seven fibrotic PM (5.5%). In 45 cases (35%), the final diagnosis was only reached by consensus. The megakaryocytic criteria that best discriminated between ET and prefibrotic-early PM were an increased nucleo-cytoplasmic ratio, presence of cloudlike nuclei, hyperchromatic-dysplastic nuclei, paratrabecular megakaryocytes and tight clusters. A histological score discriminated between ET (score < or =3) and PM (score > or =6), but 21 cases showed an intermediate ambiguous score. No significant differences were observed at diagnosis and at follow-up (median time 93 months) for thrombosis, major haemorrhage, laboratory data, transformation into overt myeloid metaplasia and survival.

CONCLUSIONS

The distinction between ET and prefibrotic-early PM is impaired by subjectivity in pathological practice and is of questionable clinical relevance, at least when considering individual patients.

Reversible phosphorylation in haematological malignancies: potential role for protein tyrosine phosphatases in treatment?

Most aspects of leukocyte physiology are under the control of reversible tyrosine phosphorylation. It is clear that excessive phosphorylation of signal transduction elements is a pivotal element of many different pathologies including haematological malignancies and accordingly, strategies that target such phosphorylation have clinically been proven highly successful for treatment of multiple types of leukemias and lymphomas. Cellular phosphorylation status is dependent on the resultant activity of kinases and phosphatases. The cell biology of the former is now well understood; for most cellular phosphoproteins we now know the kinases responsible for their phosphorylation and we understand the principles of their aberrant activity in disease. With respect to phosphatases, however, our knowledge is much patchier. Although the sequences of whole genomes allow us to identify phosphatases using in silico methodology, whereas transcription profiling allows us to understand how phosphatase expression is regulated during disease, most functional questions as to substrate specificity, dynamic regulation of phosphatase activity and potential for therapeutic intervention are still to a large degree open. Nevertheless, recent studies have allowed us to make meaningful statements on the role of tyrosine phosphatase activity in the three major signaling pathways that are commonly affected in leukemias, i.e. the Ras-Raf-ERK1/2, the Jak-STAT and the PI3K-PKB-mTOR pathways. Lessons learned from these pathways may well be applicable elsewhere in leukocyte biology as well.

Non ST-segment elevation myocardial infarction in patient with essential thrombocythemia

A 68-year-old woman presented with acute chest pain and a greatly increased platelet count. Cardiac catheterization revealed subtotal occlusion and a thrombus-like filling defect in the right coronary artery. The patient was successfully treated with intravenous tirofiban. Essential thrombocythemia was diagnosed based on bone marrow findings, clinical presentation and laboratory analysis. The relationship between intracoronary thrombus and essential thrombocythemia is discussed.

Tachykinins and Hematopoiesis

Originally discovered in the 1930s, tachykinins have been a subject of renewed interest. Antagonists to the tachykinin receptors have shown potential in the treatment of a variety of maladies including neurodegenerative disorders, heart disease, pain perception and malignancies. Tachykinins have been the subject of intense studies due to their impact on hematopoiesis that has significant effects on endothelial tissue and vascular conditions. Hematopoiesis relies on a relatively small subset of bone marrow-resident hematopoietic stem cells. This review discusses the network developed by cytokines and the tachykinins to regulate hematopoiesis. An understanding of tachykinin effect on normal hematopoietic functions and their involvement in hematological disorders could lead to new treatments for bone marrow disorders such as fibrosis, leukemia and anemia.

The chronic myeloproliferative disorders and mutation of JAK2: Dameshek's 54 year old speculation comes of age

In 1951, William Dameshek speculated on the common origin of the chronic myeloproliferative disorders--polycythemia vera (PV), essential thrombocythemia (ET), chronic idiopathic myelofibrosis (IMF), and chronic myelogenous leukemia (CML). Subsequent work suggested that all arose from the hematopoietic stem cell. About 20 years ago the oncogene responsible for CML, bcr-abl, was identified, and more recently the mutant genes that cause hypereosinophilic syndrome and systemic mast cell disorder have been discovered. However, until very recently, the origin of PV, ET, and IMF have defied molecular explanation. In 2005, four separate groups working on tyrosine kinase signal transduction reported a gain-of-function, valine-to-phenyalanine, mutation at position 617 in the JH2 domain of the Janus kinase (JAK) 2 cytoplasmic tyrosine kinase. This mutation requires the presence of the erythropoietin, thrombopoietin, or granulocyte-colony stimulating factor receptor/s for function, the mutation leads to functional hyperactivity and appears responsible for hematopoietic growth factor hypersensitivity, the most characteristic finding in these disorders. Virtually all patients with PV and substantial proportions of those with ET and IMF have now been shown to harbor this mutation. The mutant kinase appears to be a useful diagnostic test for myeloproliferative disorders and may have prognostic value. Future research will undoubtedly focus on the development of specific inhibitors as therapeutic agents as well as answering a number of questions that remain regarding the role of signal intensity, genotypic and phenotypic expression and the possible involvement of additional as yet unidentified mutations in these disorders.