Introduction:

• These are myeloid disorders that have both dysplastic and proliferative features at the time of initial presentation.
• They include
  • Chronic myelomonocytic leukemia
  • MDS/MPN with neutrophilia (Previously called atypical CML)
  • MDS/MPN with SF3B1 mutation and thrombocytosis
  • Myelodysplastic/myeloproliferative neoplasm, NOS

Chronic Myelomonocytic Leukemia

Introduction: 

• It is a clonal disorder of bone marrow stem cell with overlapping features of myelodysplastic syndrome and myeloproliferative disorders, in which monocytosis (>1000/cmm) is a major defining feature. 

Epidemiology: 

• Account for 31% of total MDS 
• Incidence- 4/1,00,000 per year 
• Common at 65-75 years 
• Male predominance 

Pathogenesis:

• Various genetic mutations lead to hypersensitivity to G-CSF
• Bone marrow has inflammatory cytokine microenvironment

Clinical Features: 

• Asymptomatic
• Proliferative symptoms (Leucocytosis related)
  • Fatigue, weight loss, fever and night sweats 
  • Bone pains
  • Splenomegaly and Hepatomegaly
  • Maculopapular skin infiltration- Leukemia cutis
  • Renal dysfunction due to high lysozyme levels 
  • Monocytic pleural/ pericardial effusion 
• Dysplastic symptoms (Cytopenia related)
  • Fatigue
  • Infections
  • Bleeding/ Bruising
• Immune manifestations (Seen in 30% patients)- Vasculitis, pyodermagangenosum, immune cytopenia, connective tissue disease, Rheumatoid arthritis
• Lymphadenopathy- Uncommon, but presence indicates probable transformation to more acute phase 

Investigations: 

• Hemogram: 
  • Monocytes- >10% in differential count, Absolute count >500/cmm 
  • Monocytes are mature with unremarkable morphology (Sometime show abnormal granulation, nuclear lobation, finely dispersed nuclear chromatin) 
  • Blasts &promonocytes may be seen – But their count  is <20% 
  • Promonocytes are monocytic precursors with abundant light gray or slightly basophilic cytoplasm with a few scattered, fine iliac-colored granules, finely-distributed, stippled nuclear chromatin, variably prominent nucleoli, and delicate nuclear folding or creasing.
  • Neutrophilia 
  • Dysgranulopoiesis – Neutrophils with hypolobulated nuclei or abnormal cytoplasmic granulation (seen especially when counts are reduced) 
  • Mild basophilia, sometimes eosinophilia 
  • Mild normocytic anemia 
  • Moderate thrombocytopenia – Atypical large platelets may be seen 
• Bone marrow aspiration and biopsy 
  • Hypercellular (in > 75% of cases) 
  • Granulocytic proliferation- Sometimes associated with dysgranulopoiesis 
  • Erythroid precursors- Increased/ decreased, sometimes with megaloblastic changes 
  • Monocytic proliferation invariably present (Identified by alpha-naphthyl butyrate esterase) 
  • Megakaryocytes – Micromegakaryocytes or megakaryocytes with abnormal lobulated nuclei 
  • Fibrosis – Variable degree (Seen in 30% patients)
  • Nodules composed of mature plasmacytoid dendritic cells- Seen in 20% cases 
  • Starry sky pattern with histiocytes containing apoptotic bodies may be seen in some cases. 
• Serum and urinary lysozyme levels – elevated 
• Cytochemistry: Monocytes are positive for Non specific esterases and lysozymes.
• Immunophenotyping 
  • Tumour cells are strongly positive for mature monocytic markers- CD11b, CD11c, CD14, CD33, CD45, CD64. 
  • Aberrant expression:
    • Positive for CD2, CD15, CD56
    • Negative for CD14, CD13, HLA-DR, CD64, or CD36.
  • Most reliable IHC markers include CD68R and CD163.
  • 3 types of monocytes can be identified by flow cytometry (Partition)
    • Classical monocytes (M01)- CD14+/CD16- 
    • Intermediate monocytes (M02)- CD14+/ CD16+ 
    • Non-classical monocytes (M03)- CD14-Low/ CD16+ 
  • In CMML- M01 type monocytes are increased (Usually >90%). Their number is decreased in reactive monocytosis. 
  • Myelomonocytic antigens  - CD33 & CD13 (sometimes CD14, CD68, CD64) 
  • Increased CD34 + cells is associated with early transformation to acute leukemias 
• Cytogenetics 
  • Nothing specific  
  • Abnormality is seen in 20 – 40% cases which include trisomy 8,-Y,  -7 / del (7q), Structural abnormalities of 12p 
  • t (5:12) – Results in abnormal fusion gene PDGFR. This is associated with marked eosinophilia (Now considered as separate entity) 
• Molecular studies by NGS panel from peripheral blood sample (>90% have somatic gene mutations)
  • Mutations in epigenetic control of transcription,such as histone modification (EZH2, ASXL1, UTX), and DNA methylation (TET2, DNMT3A, IDH1, and IDH2)
  • Mutations in the spliceosome machinery (SF3B1, SRSF2, U2AF1, ZRSR2, PRPF8)
  • Mutations in genes that regulate cell signaling (JAK2, KRAS, NRAS, CBL, PTPN11, and FLT3)
  • Mutations in transcription factors and nucleosome assembly regulators (RUNX1, SETBP1)
  • Mutations in DNA damage response genes such as TP53 and PHF6
  • TET2,ASXL1, SRSF2 and RAS gene mutation are common 
  • Hypermethylation of p15 gene – seen in 50% cases 
  • Mutation of Fibroblast growth factor receptor 1 gene on chr. 9p11 

Criteria for Diagnosis: 

• Essential criteria
  • Persistent absolute (≥ 500/cmm) and relative (≥ 10%) peripheral blood monocytosis.
  • Blasts constitute < 20% of the cells in the peripheral blood and bone marrow.
  • Not meeting diagnostic criteria of chronic myeloid leukemia or other myeloproliferative neoplasms.
  • Not meeting diagnostic criteria of myeloid/lymphoid neoplasms with eosinophilia and defining gene rearrangements (e.g. PDGFRA, PDGFRB, FGFR1, or JAK2).
• Desirable criteria
  • Dysplasia involving ≥ 1 myeloid lineages.
  • Acquired clonal cytogenetic or molecular abnormality.
  • Abnormal partitioning of peripheral blood monocyte subsets.
• Requirements for diagnosis
  • Essential criteria must be present in all cases.
  • If monocytosis is ≥ 1,000/cmm: one or more desirable criteria must be met.
  • If monocytosis is <1,000/cmm: desirable criteria 1 and 2 must be met.

Types of CMML (based on percentage of blasts and promonocytes)

• CMML-1: < 5% in peripheral blood and/or < 10% in bone marrow
• CMML-2:
  • 6-19% in peripheral blood and/or 10-19% in bone marrow
  • Auer rods are present in blasts (Irrespective of blast percentage) 

• CMML with eosinophilia 
  • Criteria for CMML are present + Peripheral blood Eosinophil count-> 1.5 x 10⁹ / L 
  • Patients have systemic complications due to degranulation from eosinophils 

FAB Classification 

• Myelodysplastic CMML: WBC Count- <13,000/cmm 
• Myeloproliferative CMML- >13,000/cmm 

Prognosis: 

• Poor prognostic factors are 
  • Anemia 
  • Thrombocytopenia 
  • Lymphocytosis 
  • Raised serum LDH 
  • Increased percentage of BM blasts 
  • Old age and poor performance score 
• Median survival: 20 – 40 months 
• Progression to AML occurs in 15-30% patients 
• Mayo molecular model
  • 1 Point each assigned to
  • Absolute monocyte count- >10,000/cmm
  • Circulating immature cells- myeloblasts, myelocytes, metamyelocytes and/or promyelocytes
  • Hemoglobin - <10gm/dL
  • Platelet count- <1,00,000/cmm
  • ASXL1 frameshift or nonsense mutation

Other risk starification methods:

• CPSS-Mol score (Includes CMML- FAB subtype, Blasts in BM, Hemoglobin, Cytogenetics, mutations observed)
• GFM Model (Includes age, WBC count, hemoglobin, platelet count and ASXL mutation status)

Indications for treatment: 

• Excess of blasts in blood or bone marrow 
• Symptoms present 
• Hemoglobin- <10gm/dL 
• Platelet count <30,000/cmm or bleeding symptoms 
• Symptomatic splenomegaly/ Other extramedullary disease- Typically cutaneous involvement or serous effusions 

Pretreatment Work-up: 

• History 
• Examination:            LN:Spleen: Skin lesions
• WHO P. S. 
• BSA 
• Flow cytometry 
• BMA and Bx 
• Haemoglobin 
• TLC, DLC 
• Abs Monocyte Count 
• Platelet count 
• Peripheral smear 
• LFT:    Bili- T/D      SGPT:          SGOT: Albumin:    Globulin: 
• Creatinine 
• Electrolytes: Na:          K:        Ca:Mg:                                 PO4: 
• Uric acid 
• LDH 
• HIV 
• HBsAg 
• HCV 
• UPT 
• USG Abdomen- Spleen size 
• Cytogenetics 
• BCR-ABL1 
• JAK-2 
• CAL-R 
• MPN 
• PDGFRA 
• PDGFRB 
• HLA Typing: For patients fit for AlloSCT
• Chemotherapy consent after informing about disease, prognosis, cost of therapy, side effects, hygiene, food and contraception 
• PICC line insertion and Chest X ray after line insertion 
• Tumor board meeting and decision 
• Attach supportive care drug sheet 
• Inform primary care physician 

Treatment Plan:

• If there is PDGFR mutation- Imatinib- 400mg-OD 

About each modalilty of treatment:

• Allo SCT-  
  • Only treatment with a chance of cure 
  • Approximately 1/3^rd patients get cured with this approach
  • Done in younger patients and patients with good PS and higher risk CMML 
  • Generally, SCT is done after achieving CR using hypomethylating agents. 
  • CR with AML like induction therapy may be necessary in CMML-2 with severe cytopenia, rapidly evolving disease, AML-M4 is a close differential diagnosis (due to presence of Auer rods) or presence of NPM1 mutation. 
  • PBSC is preferred over BM harvest 
  • Conditioning used include: Busulfan with Cyclophosphamide or TBI based regimens. In case of MUD, ATG is added. 
  • RIC conditioning may be used in patients with advanced age. 
• Hypomethulating agents (Decitabine/ Azacytidine)
  • Useful in patients with CMML-2 with WBC count <13,000/cmm, but can be used even in patients with myeloproliferative CMML.
  • Dosing same as MDS 
  • ORR- 40-50%
• Hydroxyurea 
  • Useful especially in patients with significant leukocytosis or organomegaly with absence of major cytopenias or excess of marrow blasts or renal dysfunction due to high lysozyme levels
  • Dose- 500mg- BD, then adjust the dose to target ANC of 500-1000/cmm
• Cytarabine 
• Etoposide 
• Ruxolitinib- ORR- 38%
• Supportive care including ESA or transfusions 
• Steroids: 
  • Short course may be tried if thrombocytopenia appears to be due to immune destruction 

MDS/MPN with neutrophilia

Introduction:

• It is a leukemic disorder that demonstrates both MDS & MPD features
• They have all features of CML but do not have Philadelphia chromosome / BCR-ABL fusion gene

Epidemiology:

• 1-2 cases for every 100 cases of BCR-ABL positive CML
• Common at 70-80 years

Pathogenesis:

• Mutations in ETNK1 and SETBP1 are often seen

Clinical Features:

• Anaemia
• Thrombocytopenia
• Splenomegaly

Investigations:

• Hemogram
  • WBC count variable – 35- 96 x 10⁹ /L (Always >13,000/cmm)
  • Blasts < 5%
  • Immature granulocytes (promyelocyte, myelocyte, metamyelocytes) -10-20%
  • Dysgranulopoiesis suggested by acquired Pelger – Huet& Other nuclear abnormalities and abnormal cytoplasmic granularity
  • RBC- Macro-ovalocytosis
  • Platelet count – Usually thrombocytopenia
  • Monocytosis – Up to 10%
  • Basophilia
• Bone marrow aspiration and biopsy
  • Hypercellularity due to granulocytic proliferation,
  • Blasts – Modestly increased in number (But < 20%)
  • Dysgranulopoiesis – Present
  • Megakaryocytes   – Variable count and dysplastic
  • Dyserythropoiesis present
  • Increased reticulin fibres in some cases.
• Immunophenotyping- No Specific finding
• Cytogenetics and molecular studies
  • +13, +8, del (20q), i(17q) & del (12p)
  • No BCR/ABL fusion gene
  • No PDGFR rearrangement
  • Mutations of ASXL1, TET2, and/or DNMT3A are often present
  • Other mutations include
    • Proliferative signaling pathways: CBL, JAK2, NF1, NRAS
    • Splicing machinery: SRSF2, U2AF1, SF3B1, ZRSR2
    • Transcription factors: CUX1, GATA2, RUNX1
    • Enzymes: ETNK1
    • Epigenetic regulators: SETBP1, EZH2
    • Chromosomal separation regulators: STAG2

Criteria for Diagnosis:

• Essential
  • Peripheral blood leukocytosis ≥13,000/cmm, with neutrophilia and ≥10% circulating immature myeloid cells (promyelocytes, myelocytes and metamyelocytes), as well as neutrophilic dysplasia.
  • Hypercellular bone marrow with granulocytic predominance and granulocytic dysplasia, with or without dysplasia in the megakaryocytic and erythroid lineages.
  • <20% blasts in blood and bone marrow.
  • Not meeting diagnostic criteria for myeloproliferative neoplasms (specifically, exclusion of BCR::ABL1 fusion), myeloid neoplasms with eosinophilia and defining gene rearrangement, chronic myelomonocytic leukemia, or myelodysplastic/myeloproliferative neoplasm with SF3B1 mutation and thrombocytosis.
• Desirable
  • Detection of SETBP1 and/or ETNK1 mutations.
  • Absence of mutations in JAK2, CALR, MPL, and CSF3R

Prognosis:

• Median survival: 20 months
• 15-40% evolve into AML
• Rest die because of marrow failure
• Poor prognostic markers
  • Thrombocytopenia
  • Marked anaemia<10gm/dL
  • Age >65 years
  • Female sex
  • WBC- >50,000/cmm

Pretreatment Work-up: 

• History
• Examination:           Spleen:
• WHO P. S.
• Flow cytometry
• BMA and Bx
• Haemoglobin
• TLC, DLC
• Platelet count
• Peripheral smear
• LFT: Bili- T/D   SGPT:     SGOT: Albumin:       Globulin:
• Creatinine
• Uric acid
• LDH
• HIV
• HBsAg
• HCV
• Cytogenetics
• BCR-ABL1
• JAK 2
• CAL-R
• MPN
• PDGFRA
• PDGFRB
• Chemotherapy consent after informing about disease, prognosis, cost of therapy, side effects, hygiene, food and contraception
• Tumor board meeting and decision
• Attach supportive care drug sheet
• Inform primary care physician

Treatment:

• Allogeneic stem cell transplantation in CR1
• Interferon gamma- Occasional patients achieve complete remission
• Hydroxyurea- useful as palliative treatment.

MDS/MPN with SF3B1 mutation and thrombocytosis

(MDS/MPN with ring sideroblasts and thrombocytosis)

• Median age: 68- 75 years
• Additional mutations often seen include:
  • JAK2 p.V617F
  • TET2
  • DNMT3A
  • ASXL1
  • SETBP1
  • MPL
  • SH2B3
• Hemogram
  • Macrocytic/ normocytic normochromic anemia
  • Thrombocytosis with anisocytosis
  • WBC: TLC and DC are often normal
  • Blasts: rarely seen
• Bone marrow
  • Hypercellular
  • Increased erythropoiesis with megaloblastic/ dysplastic features
  • >15% ringed sideroblasts are seen on iron staining
  • Megakaryocytes are increased and are dysmorphic
• Presents with splenemegaly
• Thrombosis risk is high
• Diagnostic criteria
  • Essential
    • Anaemia associated with dysplastic erythropoiesis and ≥15% ring sideroblasts, with or without dysplasia in the megakaryocytic and erythroid lineages. 
    • Persistent thrombocytosis, with platelet count ≥4,50,000/cmm 
    • SF3B1 mutations or, in the absence of these mutations, concurrent biologically similar mutations involving spliceosome factors and cell signaling
    • Not meeting diagnostic criteria for myelodysplastic neoplasms, myeloproliferative neoplasms, chronic myelomonocytic leukaemia, acute myeloid leukaemia with MECOM rearrangement, or myeloid/lymphoid neoplasms with eosinophilia.
  • Desirable:
    • Concurrent JAK2 p.V617F or other myeloid neoplasm associated mutations
• Prognosis: 
  • Among all MDS/MPN, it has most favorable prognosis
  • Median survival: 76- 128 months

Myelodysplastic/myeloproliferative neoplasm, NOS

• It is a myeloid neoplasm with dysplastic and proliferative features that does not meet the criteria for other defined MDS/MPN entities.
• Median age: 70 years
• Clinical features:
  • MPN-like: weight loss, night sweats, splenomegaly, and thromboembolic complications
  • MDS-like: fatigue, dyspnea, infections, and bleeding, sometimes transfusion dependent anaemia.
• Cytogenetics: 
  • Abnormal in 50% cases
  • Common abnormalities include trisomy 8, monosomy 7/deletion 7q, deletion 20q, and a monosomal or a complex karytoype.
• Molecular studies: TET2, NRAS, RUNX1, CBL, SETBP1 and ASXL1 mutations are common
• Criteria for diagnosis: Essential
  • Peripheral blood: Combination of cytopenia(s) and proliferative feature(s)
  • Bone marrow cytology: Combination of cell dysplasia and proliferative features
  • Molecular analyses of blood or bone marrow: Combination of mutations seen in proliferative and dysplastic myeloid malignancies
  • To be excluded
    • Therapy-related myeloid neoplasms
    • Disease defining gene fusions such as BCR::ABL1 fusion or rearrangement of PDGFRA, PDGFRB, JAK2 or FGFR1
    • Biallelic TP53 mutations
    • Other MDS/MPN entities, including CMML, MDS/MPN with neutrophilia (MDS/MPNN), or MDS/MPN with SF3B1 mutation and thrombocytosis 
• Prognosis: Poor with overall survival of 12- 24 months

Figures:

Figure 3.2.1- Chronic myelomonocytic leukemia- Bone marrow aspiration