Concordance among hematopathologists in classifying blasts plus promonocytes: A bone marrow pathology group study.

Enumeration of blasts and promonocytes is essential for World Health Organization (WHO) classification of myelomonocytic neoplasms. The accuracy of distinguishing blasts, promonocytes and monocytes, including normal vs abnormal monocytes, remains controversial. The objective of this analysis is to assess concordances between experienced hematopathologists in classifying cells as blasts, promonocytes, and monocytes according to WHO criteria. Each of 11 hematopathologists assessed glass slides from 20 patients [12 with chronic myelomonocytic leukemia (CMML) and 8 with acute myeloid leukemia (AML)] including blood and BM aspirate smears, and limited nonspecific esterase (NSE) stains. All cases were blindly reviewed. Fleiss' extension of Cohen's kappa for multiple raters was used on these variables, separately for peripheral blood (PB) and bone marrow (BM). Spearman's rank correlation was used to assess correlations between each pair of hematopathologists for each measurement. For the classification based on the sum of blasts and promonocytes in the BM, Fleiss' kappa was estimated as 0.744. For PB, categorizing patients according to the sum of blasts and promonocytes, Fleiss' kappa was estimated as 0.949. Distinction of abnormal monocytes from normal monocytes in PB did not achieve a good concordance and showed strong evidence of differences between hematopathologists (P < .0001). The hematopathologists achieved a good concordance rate of 74% in CMML vs AML classification and a high k rate, confirming that criteria for defining the blasts equivalents (blasts plus promonocytes) could be applied consistently. Identification of monocyte subtypes (abnormal vs normal) was not concordant. Our results support the practice of combining blasts/promonocytes into a single category.

How I investigate chronic myelomonocytic leukemia.

The 2016 revised 4th edition of the World Health Organization classification of hematopoietic neoplasms updated the diagnostic criteria for chronic myelomonocytic leukemia (CMML). Persistent peripheral blood monocytosis of at least 1 × 109 /L and a percentage of monocytes ≥10% of the circulating white blood cell count (WBC) are both prerequisite criteria for this diagnosis. CMML represents the prototype of "overlapping" myeloid neoplasms with concurrent myeloproliferative and myelodysplastic features. However, clinical presentation is heterogeneous, with cases showing prevailing "dysplastic" features and others a predominant "proliferative" phenotype. Accounting for this diversity, two variants of CMML are recognized: "dysplastic" CMML defined by WBC < 13 × 109 /L and "proliferative" CMML with WBC ≥ 13 × 109 /L often showing features mimicking a myeloproliferative neoplasm. Although not an official WHO category, the "oligomonocytic" variant of CMML is defined by relative monocytosis with an absolute monocyte count of 0.5-0.9 × 109 /L. It can be considered a "pre-phase," as it frequently anticipates the development of an overt, classic CMML. In an attempt at improving disease prognostication, the blast count based grading system for CMML of the WHO 2008 Classification has been expanded in 2016 to include a new "CMML-0" category. Lastly, the large body of knowledge on the molecular events occurring in CMML has been used to assist diagnosis and assess prognosis. Despite the step forwards, diagnosis of CMML still remains one of exclusion as no clinical, pathologic or molecular findings are specific for this disease. The current review brings insight into the spectrum of CMML and provides practical advice to approach suspected cases of CMML.

Heterogeneous expression of cytokines accounts for clinical diversity and refines prognostication in CMML.

Chronic myelomonocytic leukemia (CMML) is a clinically heterogeneous neoplasm in which JAK2 inhibition has demonstrated reductions in inflammatory cytokines and promising clinical activity. We hypothesize that annotation of inflammatory cytokines may uncover mutation-independent cytokine subsets associated with novel CMML prognostic features. A Luminex cytokine profiling assay was utilized to profile cryopreserved peripheral blood plasma from 215 CMML cases from three academic centers, along with center-specific, age-matched plasma controls. Significant differences were observed between CMML patients and healthy controls in 23 out of 45 cytokines including increased cytokine levels in IL-8, IP-10, IL-1RA, TNF-α, IL-6, MCP-1/CCL2, hepatocyte growth factor (HGF), M-CSF, VEGF, IL-4, and IL-2RA. Cytokine associations were identified with clinical and genetic features, and Euclidian cluster analysis identified three distinct cluster groups associated with important clinical and genetic features in CMML. CMML patients with decreased IL-10 expression had a poor overall survival when compared to CMML patients with elevated expression of IL-10 (P = 0.017), even when adjusted for ASXL1 mutation and other prognostic features. Incorporating IL-10 with the Mayo Molecular Model statistically improved the prognostic ability of the model. These established cytokines, such as IL-10, as prognostically relevant and represent the first comprehensive study exploring the clinical implications of the CMML inflammatory state.

The 2016 WHO versus 2008 WHO Criteria for the Diagnosis of Chronic Myelomonocytic Leukemia.

The 2016 WHO diagnostic criteria for chronic myelomonocytic leukemia (CMML) require both absolute and relative monocytosis (≥1×109/L and ≥10% of white blood cell counts) in peripheral blood. Moreover, myeloproliferative neoplasm (MPN) features in bone marrow and/or MPN-associated mutations tend to support MPN with monocytosis rather than CMML. We assessed the impact of the 2016 WHO criteria on CMML diagnosis, compared with the 2008 WHO criteria, through a retrospective review of the medical records of 38 CMML patients diagnosed according to the 2008 WHO classification. Application of the 2016 WHO criteria resulted in the exclusion of three (8%) patients who did not fulfill the relative monocytosis criterion and eight (21%) patients with an MPN-associated mutation. These 11 patients formed the 2016 WHO others group; the remaining 27 formed the 2016 WHO CMML group. The significant difference in the platelet count and monocyte percentage between the two groups indicated that the 2016 WHO criteria lead to a more homogenous and improved definition of CMML compared with the 2008 WHO criteria, which may have led to over-diagnosis of CMML. More widespread use of molecular tests and more sophisticated clinical and morphological evaluations are necessary to diagnose CMML accurately.

Oligomonocytic chronic myelomonocytic leukemia (chronic myelomonocytic leukemia without absolute monocytosis) displays a similar clinicopathologic and mutational profile to classical chronic myelomonocytic leukemia.

Chronic myelomonocytic leukemia is characterized by persistent absolute monocytosis (≥1 × 109/l) in the peripheral blood and dysplasia in ≥1 lineages. In the absence of dysplasia, an acquired clonal genetic abnormality is required or causes for reactive monocytosis have to be excluded. Oligomonocytic chronic myelomonocytic leukemia showing increased monocytes but no absolute monocytosis in the peripheral blood occurs occasionally. These cases are likely classified as myelodysplastic syndrome or myelodysplastic/myeloproliferative neoplasm, unclassifiable. A subset eventually develop overt chronic myelomonocytic leukemia. Better characterization of oligomonocytic chronic myelomonocytic leukemia is essential since the distinction between chronic myelomonocytic leukemia and myelodysplastic syndrome is clinically relevant. We identified 44 cases of oligomonocytic chronic myelomonocytic leukemia (≥10% peripheral blood monocytes with absolute monocyte count of 0.5-1 × 109/l) and 28 consecutive chronic myelomonocytic leukemia controls. Clinicopathologic features were compared and mutation analysis was performed. Oligomonocytic chronic myelomonocytic leukemia patients were significantly younger (median age of 65 vs 72). They had lower WBC and absolute neutrophil count, while the monocyte percentage, hemoglobin and platelet counts were similar in the two groups. The myeloid to erythroid ratio was predominantly decreased or normal, compared with the characteristic increase in chronic myelomonocytic leukemia (P=0.006). 38% of patients progressed to overt chronic myelomonocytic leukemia (median: 12 months). The overall percentage of mutations was significantly lower in oligomonocytic chronic myelomonocytic leukemia. However, the most frequent mutations in both groups were the 'signature' chronic myelomonocytic leukemia mutations in ASXL1, TET2 and SRSF2. Mutations in CBL were found exclusively in overt chronic myelomonocytic leukemia. In conclusion, we demonstrate clinical and genetic similarities between overt chronic myelomonocytic leukemia and oligomonocytic chronic myelomonocytic leukemia. The findings suggest that at least a subset of oligomonocytic chronic myelomonocytic leukemia represents early phase 'dysplastic type' chronic myelomonocytic leukemia.

When clinical heterogeneity exceeds genetic heterogeneity: thinking outside the genomic box in chronic myelomonocytic leukemia.

Exome sequencing studies in chronic myelomonocytic leukemia (CMML) illustrate a mutational landscape characterized by few somatic mutations involving a subset of recurrent gene mutations in ASXL1, SRSF2, and TET2, each approaching 40% in incidence. This has led to the clinical implementation of next-generation sequencing panels that effectively identify clonal monocytosis and complement clinical prognostic scoring systems in most patients. However, most murine models based on single gene mutations fail to recapitulate the CMML phenotype, and many gene mutations are loss of function, making the identification of traditional therapeutic vulnerabilities challenging. Further, as a subtype of the myelodysplastic/myeloproliferative neoplasms, CMML has a complex clinical heterogeneity not reflected by the mutational landscape. In this review, we will discuss the discordance between mutational homogeneity and clinical complexity and highlight novel genomic and nongenomic approaches that offer insight into the underlying clinical characteristics of CMML.

Immunophenotypes of Chronic Myelomonocytic Leukemia (CMML) Subtypes by Flow Cytometry: A Comparison of CMML-1 vs CMML-2, Myeloproliferative vs Dysplastic, De Novo vs Therapy-Related, and CMML-Specific Cytogenetic Risk Subtypes.

OBJECTIVES: We sought to immunophenotype blasts, monocytes, and granulocytes in chronic myelomonocytic leukemias (CMMLs) and compare CMML subtypes, to identify if significant antigen expression differences existed. METHODS: Bone marrow blasts, monocytes, and granulocytes from CMML subgroups (n = 30; World Health Organization types 1/2, proliferative/dysplastic, therapy related/de novo, and low/intermediate/high cytogenetic risk) were immunophenotypically compared by flow cytometry with 10 nonneoplastic control marrows. RESULTS: Aberrancies were present in blasts of 26 (87%) of 30 CMMLs (26 diagnostic; four follow-up) and six (60%) of 10 controls (P = .089), monocytes of 28 (93%) of 30 CMMLs and six (60%) of 10 controls (P = .026), and granulocytes of eight (28%) of 29 CMMLs and zero of 10 controls (P = .166). Underexpression of CD14 and CD15 on monocytes was more common in CMMLs compared with controls (P = .008 and P = .043). Statistical analysis showed no significant difference in antigen expression between the CMML subgroups on blasts or monocytes; granulocytes demonstrated more common HLA-DR expression in CMML-2 vs CMML-1. CONCLUSIONS: These findings confirm heterogeneity within CMML subgroups and find no specific qualitative or quantitative findings characteristic of a subgroup.

Chronic myelomonocytic leukemia prognostic classification and management: evidence base and current practice.

Chronic myelomonocytic leukemia is a clonal malignancy of the ageing hematopoietic stem cell characterized by a biased differentiation leading to persistent monocytosis and inconstant hypersensitivity of myeloid progenitors to granulo-monocyte colony-stimulating factor (GM-CSF). Cytogenetic abnormalities identified in 30-40 % of patients and gene mutations detected in every patient can be used to stratify patients into risk groups that guide the therapeutic choices. TET2, SRSF2, ASXL1, and genes of the Ras pathway are the most frequently mutated genes, with ASXL1 mutations negatively affecting the disease outcome. Allogeneic stem cell transplantation is the first option to consider, especially in younger patients with poor prognostic factors. There is no firm clinical guideline in transplant-ineligible patients, but hypomethylating agents might be an interesting option. A consensus prognostic scoring system and specific response criteria are now required to facilitate the evaluation of new therapeutic strategies in clinical trials specifically dedicated to this disease.

Cytogenetic risk stratification of 417 patients with chronic myelomonocytic leukemia from a single institution.

Approximately 30% of patients with chronic myelomonocytic leukemia (CMML) have karyotypic abnormalities and this low frequency has made using cytogenetic data for the prognostication of CMML patients challenging. Recently, a three-tiered cytogenetic risk stratification system for CMML patients has been proposed by a Spanish study group. Here we assessed the prognostic impact of cytogenetic abnormalities on overall survival (OS) and leukemia-free survival (LFS) in 417 CMML patients from our institution. Overall, the Spanish cytogenetic risk effectively stratified patients into different risk groups, with a median OS of 33 months in the low-, 24 months in intermediate- and 14 months in the high-risk groups. Within the proposed high risk group, however, marked differences in OS were observed. Patients with isolated trisomy 8 showed a median OS of 22 months, similar to the intermediate-risk group (P = 0.132), but significantly better than other patients in the high-risk group (P = 0.018). Furthermore, patients with more than three chromosomal abnormalities showed a significantly shorter OS compared with patients with three abnormalities (8 vs. 15 months, P = 0.004), suggesting possible a separate risk category. If we simply moved trisomy 8 to the intermediate risk category, the modified cytogenetic grouping would provide a better separation of OS and LFS; and its prognostic impact was independent of other risk parameters. Our study results strongly advocate for the incorporation of cytogenetic information in the risk model for CMML.

Gene mutations differently impact the prognosis of the myelodysplastic and myeloproliferative classes of chronic myelomonocytic leukemia.

Initially classified in the myelodysplastic syndromes (MDSs), chronic myelomonocytic leukemia (CMML) is currently considered as a MDS/myeloproliferative neoplasm. Two classes-myelodysplastic and myeloproliferative-have been distinguished upon the level of the white blood cell count (threshold 13 G/L). We analyzed mutations in 19 genes reported in CMML to determine if and how these mutations impacted the respective prognosis of the two classes. We defined four major mutated pathways (DNA methylation, ASXL1, splicing, and signaling) and determined their prognostic impact. The number of mutated pathways impacted overall survival in the myelodysplastic class but not in the myeloproliferative class. The myeloproliferative class had a worse prognosis than the myelodysplastic class and was impacted by RUNX1 mutations only. Our results argue for a reclassification of CMML based on the myelodysplastic/myeloproliferative status.

Refined diagnostic criteria and classification of mast cell leukemia (MCL) and myelomastocytic leukemia (MML): a consensus proposal.

Mast cell leukemia (MCL), the leukemic manifestation of systemic mastocytosis (SM), is characterized by leukemic expansion of immature mast cells (MCs) in the bone marrow (BM) and other internal organs; and a poor prognosis. In a subset of patients, circulating MCs are detectable. A major differential diagnosis to MCL is myelomastocytic leukemia (MML). Although criteria for both MCL and MML have been published, several questions remain concerning terminologies and subvariants. To discuss open issues, the EU/US-consensus group and the European Competence Network on Mastocytosis (ECNM) launched a series of meetings and workshops in 2011-2013. Resulting discussions and outcomes are provided in this article. The group recommends that MML be recognized as a distinct condition defined by mastocytic differentiation in advanced myeloid neoplasms without evidence of SM. The group also proposes that MCL be divided into acute MCL and chronic MCL, based on the presence or absence of C-Findings. In addition, a primary (de novo) form of MCL should be separated from secondary MCL that typically develops in the presence of a known antecedent MC neoplasm, usually aggressive SM (ASM) or MC sarcoma. For MCL, an imminent prephase is also proposed. This prephase represents ASM with rapid progression and 5%-19% MCs in BM smears, which is generally accepted to be of prognostic significance. We recommend that this condition be termed ASM in transformation to MCL (ASM-t). The refined classification of MCL fits within and extends the current WHO classification; and should improve prognostication and patient selection in practice as well as in clinical trials.