Haematology · General Medicine

Myelodysplastic Syndromes

Also known as Myelodysplastic syndrome · MDS · Myelodysplasia · Preleukaemia · Smouldering leukaemia

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal haematopoietic stem-cell neoplasms defined by dysplastic, ineffective haematopoiesis, peripheral cytopenia(s) and a variable risk of transformation to acute myeloid leukaemia. Diagnosis requires dysplasia of at least 10 percent in one or more myeloid lineages (or an MDS-defining cytogenetic lesion) plus a persistent unexplained cytopenia after excluding secondary causes (B12, folate, copper deficiency, alcohol, infection). The 20 percent blast threshold separates MDS from AML. Risk is stratified by the IPSS-R and, increasingly, the molecular IPSS-M (blast percentage, cytogenetics, haemoglobin, platelets, plus TP53, SF3B1, FLT3 mutations). Lower-risk disease is managed with supportive care, erythropoiesis-stimulating agents, lenalidomide for del(5q) and luspatercept for ringed sideroblasts; higher-risk disease gets a hypomethylating agent (azacitidine or decitabine), often with venetoclax and the only curative modality — allogeneic stem-cell transplant. Median survival spans from over eight years in very-low-risk disease to under a year in very-high-risk or multi-hit TP53 disease.

High yieldHigh evidenceUpdated 26 July 202617 min readVerification in progress

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Red flags

  • Older adult with persistent macrocytic cytopenia and dysplastic film — MDS; send bone marrow with cytogenetics and exclude B12/folate/copper deficiency
  • Marrow or blood blasts at least 20 percent — this is AML, not MDS; urgent haematology referral
  • Chronic transfusion with ferritin over 1000 microg/L — start iron chelation to protect liver, heart and endocrine function
  • Fit higher-risk MDS patient — early donor search and transplant referral; allogeneic SCT is the only cure
  • Cytopenia with vacuolated precursors and neuropathy after gastric surgery — copper deficiency mimics MDS; check serum copper

Meet the patient

A 76-year-old man is referred for a macrocytic anaemia found on routine bloods. His MCV is raised, his platelet count is modestly reduced, and the film shows hypogranular neutrophils and a few pseudo-Pelger-Huët cells. His B12, folate and thyroid are normal, he does not drink heavily, and his copper level is normal.[1]

He is a classic MDS presentation — an older adult with a macrocytic cytopenia and dysplastic film, with the nutritional and toxic mimics excluded. The marrow biopsy will give the clonal plasma-cell... no, the clonal haematopoietic picture, the blast percentage, the cytogenetics and the molecular profile that drive the entire management fork: is this lower-risk disease to support, or higher-risk disease to treat?[1]

The paradox — a cellular marrow with empty blood

Myelodysplastic syndromes are clonal haematopoietic stem-cell neoplasms in which ineffective haematopoiesis produces one or more persistent peripheral cytopenias — anaemia most often, but also neutropenia and thrombocytopenia — with a variable propensity to transform into acute myeloid leukaemia. They are the commonest myeloid malignancy of older adults.[1]

The central lesion is ineffective haematopoiesis: the clone proliferates but its offspring die by apoptosis before reaching the blood. The result is the paradox that defines MDS — a hyper- or normocellular marrow producing peripheral cytopenia, the opposite of the empty marrow of aplastic anaemia. A parallel process of blast accumulation and clonal evolution accounts for progression to AML in about a quarter to a third of patients. The 20 percent marrow or peripheral blast threshold separates MDS from AML (the WHO lowered the old FAB 30 percent to 20 percent in 2001).[1][7]

The diagnostic triad — DYC

The diagnosis rests on a triad that an examiner will always probe:[1]

  1. Dysplasia of at least 10 percent in one or more myeloid lineages (erythroid, granulocytic, megakaryocytic), or an MDS-defining cytogenetic abnormality such as isolated del(5q).
  2. A persistent unexplained cytopenia (at least four to six months, not attributable to a secondary cause).
  3. Exclusion of secondary and reactive causes — vitamin B12 and folate deficiency, copper deficiency, alcohol, viral infection (HIV, parvovirus B19), and drug effect.[1]
The MDS diagnostic triad

DYC

  • DDysplasiaat least 10 percent in one or more myeloid lineages (or an MDS-defining cytogenetic lesion such as isolated del(5q))
  • YYtopeniaa persistent unexplained cytopenia (anaemia, neutropenia or thrombocytopenia) for at least four to six months
  • CCauses excludedrule out B12, folate, copper deficiency, alcohol, HIV and drugs before calling it MDS
[1]

WHO 2022 classification — genetics now runs the show

MDS classification has moved from morphology alone (the 1982 FAB system) to the WHO 5th edition (2022) and the parallel International Consensus Classification (ICC, 2022), both reorganising the disease around genetics. The thresholds a student must reproduce are the 10 percent dysplasia cut-off, the 5 percent blast line separating low-blast from high-blast MDS, and the 20 percent blast line that defines AML.[7]

MDS with low blasts and isolated del(5q) — the 5q- syndrome

  • Macrocytic anaemia with or without other cytopenia, isolated del(5q), under 5 percent marrow and under 2 percent blood blasts
  • Classically favourable prognosis; high response to lenalidomide
  • Female predominance; one of the most distinctive MDS subtypes

MDS with low blasts and SF3B1 mutation (MDS-SF3B1)

  • Under 5 percent blasts, an SF3B1 mutation, 15 percent or more ringed sideroblasts
  • Favourable prognosis; superior response to luspatercept
  • Replaces the old RARS and RCMD-RS categories

MDS with low blasts (MDS-LB)

  • Under 5 percent marrow and under 2 percent blood blasts; dysplasia in one (single-lineage) or more (multilineage) lineages
  • The most common morphological category; generally lower risk
  • ESA-responsive if the serum EPO is low

MDS with increased blasts — MDS-IB

  • MDS-IB1: 2 to 9 percent blood blasts or 5 to 9 percent marrow blasts
  • MDS-IB2: 5 to 19 percent blood or 10 to 19 percent marrow blasts, or Auer rods
  • Higher risk of infection, bleeding and AML transformation; needs disease-modifying therapy and transplant consideration
  • Replaces the older MDS-EB1 and MDS-EB2 names

MDS with biallelic TP53 inactivation (MDS-biTP53)

  • Two or more TP53 hits (mutations, deletion or copy-neutral loss of heterozygosity), often a complex karyotype
  • Frequent in therapy-related MDS; aggressive with early AML transformation
  • Very poor prognosis; HMA-based therapy and selected transplant

MDS with fibrosis (MDS-f) and MDS, NOS

  • MDS-f: marked reticulin fibrosis with dysplasia; often a dry tap, diagnosed on the trephine
  • MDS, NOS: morphologically defined MDS when genetics are unavailable
  • Hypoplastic MDS (cellularity under 25 percent for age) sits here and may respond to immunosuppression
[7]

The older FAB classification is still encountered: refractory anaemia (RA), RA with ringed sideroblasts (RARS), RA with excess blasts (RAEB), RAEB in transformation (now reclassified as AML), refractory cytopenia with multilineage dysplasia (RCMD), and the 5q- syndrome. Chronic myelomonocytic leukaemia (CMML) is no longer MDS — it is an MDS/MPN overlap neoplasm defined by persistent peripheral monocytosis of at least 1.0×10⁹/L.[1]

FigureMDS spans a risk spectrum. Lower-risk categories (left) — MDS with low blasts, isolated del(5q) and SF3B1-mutated ringed-sideroblast disease — carry near-normal to moderately reduced survival and respond to erythropoiesis-stimulating agents, lenalidomide and luspatercept. Higher-risk categories (right) — MDS-IB2 and MDS-biTP53 — carry short survival and a high AML-transformation risk, managed with a hypomethylating agent (plus venetoclax) and allogeneic transplant.

The 20 percent line — where MDS becomes AML

WHO 2022 and ICC 2022 agree on most categories and both retain the 20 percent blast threshold for AML when no defining AML genetics are present. They recognise MDS-biTP53 and the SF3B1 and del(5q) genetic entities. The ICC, however, sets the AML threshold at 10 percent blasts for cases with a defining AML genetic abnormality (such as t(8;21) or an NPM1 mutation), and merges some low-blast categories. In practice, treat the IPSS-R and IPSS-M risk scores — not the classification name — as the primary guide to therapy.[7]

Who gets it — and the CHIP spectrum

MDS has an overall incidence of about 4 per 100,000 per year, rising to over 30 per 100,000 in those over 70. The median age is about 76 with a slight male predominance. It is substantially more common than AML in the elderly.[1]

Recognised acquired and environmental risk factors:[1]

  • Increasing age (the dominant factor — clonal haematopoiesis becomes almost universal beyond 70), male sex, tobacco smoking, benzene and solvent exposure, and ionising radiation.
  • Prior cytotoxic therapy — the single most important modifiable risk factor.[1]

Therapy-related MDS (t-MDS) arises after chemo- or radiotherapy and carries two subtypes: an alkylating-agent or radiation-related form (latency 5 to 7 years, chromosomes 5 and 7 abnormalities, complex karyotype, TP53 mutation, poor prognosis) and a topoisomerase-II-inhibitor-related form (latency 2 to 3 years, balanced translocations of 11q23/KMT2A or RUNX1, often presenting as AML).[1]

The antecedent spectrum explains most "de novo" MDS. Clonal haematopoiesis of indeterminate potential (CHIP) — a somatic mutation (DNMT3A, TET2, ASXL1, TP53, JAK2) at a variant allele fraction of at least 2 percent in someone with a normal count — is detectable in over 10 percent of people over 70. Add an unexplained cytopenia without enough dysplasia to call MDS and it is clonal cytopenia of undetermined significance (CCUS); without a clone it is idiopathic cytopenia of undetermined significance (ICUS).[1]

Inherited bone-marrow-failure and germline-predisposition syndromes (Fanconi anaemia, Shwachman-Diamond, dyskeratosis congenita and other telomere-biology disorders, and germline GATA2, RUNX1, ETV6, DDX41 and CEBPA) evolve to MDS — a young patient with MDS should trigger germline testing, which changes donor selection and conditioning.[1]

The mechanism — ineffective haematopoiesis

An acquired somatic mutation in a multipotent haematopoietic stem or progenitor cell confers a clonal advantage, and the disease then evolves through multiple genetic hits:[1]

  • Early founding mutations in DNA-methylation and chromatin genes — TET2, DNMT3A, ASXL1 — shared with CHIP and establish the clone.
  • Spliceosome mutations (SF3B1, SRSF2, U2AF1, ZRSR2) commonly follow; SF3B1 is the hallmark of ringed-sideroblast disease.
  • Late, progression-associated mutationsTP53 (multi-hit), RUNX1, EZH2, NRAS or KRAS, FLT3, IDH1 or IDH2 — drive blast accumulation and evolution to AML.[1]
FigureTwo parallel disease processes from one founding clone. On the left, dysplastic progenitors die within the marrow (ineffective haematopoiesis) — failing to make adequate red cells (anaemia), neutrophils (infection) and platelets (bleeding) despite a cellular marrow. On the right, the same clone accumulates blasts, acquiring further mutations (TP53, RUNX1, RAS) and progressing to AML.

The dominant consequence is ineffective haematopoiesis: maturing progenitors undergo excessive intramedullary apoptosis (up to three times normal), so the marrow is frequently hyper- or normocellular while the blood is cytopenic. A pro-inflammatory, dysfunctional marrow microenvironment selectively favours the clone.[1]

Recurrent cytogenetic lesions and their prognostic signal:[2]

  • Favourable or good: isolated del(5q), del(20q), -Y, a normal karyotype (about half of all MDS).
  • Intermediate: del(7q), trisomy 8 (+8), i(17q).
  • Adverse or poor: monosomy 7 (-7), del(5q) with other abnormalities, inv(3) or t(3;3), a complex karyotype (at least 3 unrelated abnormalities); multi-hit TP53 commonly coexists with a complex karyotype.[2]

Recurrent gene mutations: SF3B1 (ringed sideroblasts — favourable); TP53 multi-hit (complex karyotype, therapy-related — very adverse); ASXL1, RUNX1, EZH2, NRAS or KRAS (adverse); TET2, DNMT3A (common, largely intermediate). These — captured by the molecular IPSS-M — refine prognosis well beyond the IPSS-R.[1][5]

How it walks in — usually an incidental count

The commonest presentation is an incidental finding of cytopenia, macrocytosis or dysplastic morphology on a routine full blood count in an older adult — frequently asymptomatic. When symptoms occur they reflect the affected lineage:[1]

  • Anaemia (present in over 80 percent at diagnosis) — fatigue, pallor, exertional dyspnoea, worsening of angina or cardiac failure.
  • Neutropenia — recurrent bacterial infection (chest, skin, perianal), fever, and occasionally neutropenic sepsis as the first clue.
  • Thrombocytopenia — easy bruising, petechiae, purpura, mucosal bleeding, menorrhagia.[1]

Bicytopenia or pancytopenia is common; an isolated cytopenia (usually anaemia) is the other pattern. Splenomegaly and lymphadenopathy are uncommon in MDS — their presence should prompt consideration of an MDS/MPN overlap syndrome (CMML), primary myelofibrosis, CML, or a separate lymphoid process.[1]

Atypical and paraneoplastic presentations that examiners test deliberately: acute febrile neutrophilic dermatosis (Sweet syndrome) and cutaneous vasculitis may accompany or precede MDS, as may autoimmune phenomena. In the very elderly, MDS may present as isolated fatigue, falls, delirium, or an exacerbation of cardiac failure from unrecognised anaemia.[1]

The differential — dysplasia alone is not MDS

Dysplasia alone is not MDS — reactive and secondary causes must be excluded before diagnosing a clonal disorder. This single principle generates more exam questions than any other in the topic.[1]

Nutritional deficiencies

  • Vitamin B12 and folate deficiency — megaloblastic change with hypersegmented neutrophils and macro-ovalocytes; check serum B12 and RBC folate
  • Copper deficiency — anaemia plus neutropenia with vacuolated erythroid and myeloid precursors and ringed sideroblasts; a sensory (dorsal-column) neuropathy; classic after gastric or bariatric surgery or zinc excess; a notorious MDS mimic
  • Corrects with replacement — the MDS diagnosis is only safe once these are normal

Toxic, drug and infectious mimics

  • Alcohol excess — macrocytosis, vacuolated red-cell precursors, thrombocytopenia
  • Drug effect — chemotherapy, antibiotics, immunosuppressants, myelotoxic agents
  • Viral infection — HIV (cytopenias with mild dysplasia), parvovirus B19 (pure red-cell aplasia), EBV, CMV, hepatitis
  • Heavy metals — lead (basophilic stippling), arsenic

Other clonal and marrow-failure disorders

  • Aplastic anaemia — hypocellular marrow without dysplasia or a clone
  • Large granular lymphocytic leukaemia — pure red-cell aplasia, chronic neutropenia, rheumatoid arthritis
  • Paroxysmal nocturnal haemoglobinuria — haemolysis, cytopenia, thrombosis; flow cytometry (FLAER) defines it
  • Primary myelofibrosis — teardrop cells, splenomegaly, marked fibrosis
  • Overt AML — blasts at least 20 percent

Borderline pre-MDS states

  • CHIP — a clone (DNMT3A or TET2 or ASXL1 or TP53 or JAK2 VAF at least 2 percent) but a normal count
  • CCUS — a clone plus an unexplained cytopenia but insufficient dysplasia or genetics to call MDS
  • ICUS — an unexplained cytopenia without a clone
  • Observation and re-biopsy resolve most; do not over-treat
[1]

The single most important teaching point: always send B12, folate and a serum copper level, take an alcohol and drug history, and exclude HIV before labelling dysplasia as MDS.[1]

The bedside round

The focused assessment documents the consequences of the cytopenia, screens for alternative diagnoses, and gathers the information that drives intensity of therapy (especially transplant eligibility).[1]

Run it in order: general (pallor, bruising, petechiae and purpura, infection; document performance status and comorbidity burden — both gate transplant decisions); abdomen (hepatosplenomegaly suggests an overlap syndrome, CMML, myelofibrosis or infiltration; lymphadenopathy suggests lymphoma); cardiovascular (the consequences of anaemia — tachycardia, a flow murmur, cardiac failure); and a focused drug, occupational (benzene, solvents, radiation) and prior-cancer-treatment exposure history, plus a family history of haematological malignancy (germline predisposition).[1]

There are no pathognomonic bedside signs of MDS — the diagnosis is made in the laboratory.[1]

Investigations — the marrow and the iron stain

First-line bloods: full blood count and film (macrocytosis — MCV often 100 to 120 fL, hypogranular or hyposegmented pseudo-Pelger-Huët neutrophils, giant hypogranular platelets, inappropriately low reticulocytes, a peripheral blast count), LDH (raised in higher-risk disease), and a screen to exclude secondary causes (B12, folate, copper, ferritin, HIV, an alcohol history).[1]

Bone-marrow aspirate and trephine biopsy is the diagnostic cornerstone and every patient needs one:[1]

  • Cellularity — hyper-, normo- or hypocellular (hypoplastic MDS mimics aplastic anaemia).
  • Dysplasia of at least 10 percent — erythroid (nuclear budding, multinucleation, ringed sideroblasts), granulocytic (hypogranular, hyposegmented Pelgeroid forms), megakaryocytic (micromegakaryocytes).
  • Blast percentage — counted precisely (the 5, 10 and 20 percent lines all matter).
  • Prussian-blue (Perls) iron stain — for ringed sideroblasts (erythroid precursors with at least 5 siderotic granules encircling at least one-third of the nucleus); 15 percent or more with an SF3B1 mutation defines MDS-SF3B1.
  • Reticulin fibrosis — grades MDS-f.[1]

Cytogenetics: conventional G-banding karyotype plus FISH for the common lesions (-7 or del(7q), del(5q), del(20q), trisomy 8, complex karyotype). Molecular next-generation sequencing for TP53, SF3B1, ASXL1, RUNX1, TET2, EZH2, NRAS, FLT3, IDH1 or IDH2 refines prognosis and guides therapy — lenalidomide for del(5q), venetoclax consideration, TP53-directed trials.[1]

Erythropoietin level — in a validated predictive model, a serum EPO of 500 U/L or less together with a transfusion need of under 2 units per month predicted a high probability of erythroid response to erythropoietin-based therapy, whereas both markers being adverse predicted a poor response.[9]

Risk stratification — IPSS-R and the molecular IPSS-M

Risk stratification drives every management decision. The IPSS-R (Greenberg, Blood 2012) is built on marrow cytogenetics, blast percentage and the depth of cytopenias, and defines five risk categories; the IPSS-M (Bernard, NEJM Evidence 2022) layers gene-mutation data on top and restratified 46 percent of patients relative to the IPSS-R.[2][5]

The IPSS-R combines marrow blast percentage (with the low blast value split), cytogenetic risk group (five subgroups rather than the original IPSS three), and the depth of cytopenias:[2]

IPSS-R cytogenetic risk groups
Cytogenetic groupRepresentative abnormalitiesPrognostic weight
Very good-Y, del(11q)favourable
GoodNormal, isolated del(5q), del(20q), del(12p)favourable
Intermediatedel(7q), +8, i(17q), +19, other single or independent double abnormalitiesintermediate
Poorinv(3) or t(3q), -7, double abnormalities, complex (3 abnormalities)adverse
Very poorComplex karyotype (more than 3 abnormalities)very adverse
[1]

The marrow blast percentage, the cytogenetic risk group and the depth of cytopenias combine into a score distributing patients into five prognostic categories (rather than the four categories of the original IPSS):[2]

IPSS-R risk categories

Intermediate

Intermediate features across blasts, cytogenetics and cytopenias — intermediate prognosis

[2]

The molecular IPSS-M incorporates the IPSS-R clinical variables plus 31 gene mutations — weighted most heavily for multi-hit TP53 (adverse) and SF3B1 (favourable), with FLT3 also adverse:[5]

IPSS-M risk categories

Very Lowlowest riskfavourable genetics, low blasts
Lowlow riskfavourable mutation profile
Moderate-Lowmoderate-low riskintermediate genetics
Moderate-Highmoderate-high riskadverse features accumulating
Highhigh riskadverse mutations or cytogenetics
Very Highhighest riskmulti-hit TP53, adverse genetics
[5]

In practice, the IPSS-M restratified 46 percent of patients relative to the IPSS-R — which is why molecular testing is now standard in fit patients. Iron-overload monitoring: in the randomised TELESTO trial, deferasirox chelation in transfusion-dependent, iron-overloaded lower-risk patients (ferritin over 2247 pmol/L, about 1000 micrograms per litre) prolonged event-free survival, supporting chelation in this group.[5][11]

The first threats — anaemia, bleeding, neutropenic sepsis

FigureRisk-adapted therapy. Lower-risk disease (left) — erythropoiesis-stimulating agents, lenalidomide for del(5q), luspatercept for ringed sideroblasts, transfusion and iron chelation. Higher-risk disease (right) — a hypomethylating agent (azacitidine or decitabine), often with venetoclax, and allogeneic stem-cell transplant (the only cure) in fit patients. Immunoglobulin and antimicrobial prophylaxis, and iron chelation, span both pathways.
[1]

Treat the acute cytopenic consequences first, then start risk-adapted disease therapy. The immediate threats are severe symptomatic anaemia, major bleeding, and neutropenic sepsis.[1]

  • Severe or symptomatic anaemia — red-cell transfusion, titrated to the lowest level that relieves symptoms; transfusion need is itself a driver of risk assessment and therapy selection.
  • Thrombocytopenia — platelet transfusion for active bleeding or before procedures.
  • Febrile neutropenia — a medical emergency: blood cultures then empirical broad-spectrum antipseudomonal beta-lactam cover; the IDSA guideline standardises antimicrobial use in cancer patients with fever and neutropenia.[15]
  • Iron overload from chronic transfusion — the randomised TELESTO trial supports deferasirox chelation in iron-overloaded, transfusion-dependent lower-risk patients.[11]
[1] [15]

Lower-risk MDS — supportive and growth-factor therapy

Therapy is risk-adapted using the IPSS-R (and increasingly IPSS-M) and calibrated to age, fitness and goals. Lower-risk disease (IPSS-R very low, low, and many intermediate) is managed with supportive care and growth factors. The aim is to relieve cytopenia, improve quality of life and delay transformation — not to eradicate the clone.[1][3]

Lower-risk MDS — the stepwise ladder

  1. 1

    Supportive care for all — red-cell and platelet transfusion as needed; iron chelation (deferasirox) in the transfusion-dependent, iron-overloaded patient (TELESTO).

  2. 2

    Erythropoiesis-stimulating agents when serum EPO is 500 U/L or less and transfusion need is under 2 units per month — the validated predictive model for erythroid response; in a phase 3 trial, darbepoetin alfa 500 microg subcutaneously every 3 weeks reduced transfusion incidence versus placebo.

  3. 3

    Luspatercept 1.0 up to 1.75 mg/kg subcutaneously every 3 weeks for ringed-sideroblast, lower-risk MDS after ESA failure (MEDALIST: transfusion independence for 8 weeks or longer in 38 versus 13 percent).

  4. 4

    Lenalidomide 10 mg orally daily, 21 of every 28 days, for del(5q) MDS — transfusion independence in 67 percent and cytogenetic improvement in the majority of evaluable patients.

  5. 5

    Re-assess with marrow and cytogenetics; escalate to an HMA if blasts rise or transfusion dependence develops.

[1] [4] [6] [9] [10] [11]

Lower-risk MDS — erythropoiesis-stimulating agents and targeted therapy

[4] [6] [9] [10] [11]

Higher-risk MDS — HMA, venetoclax, transplant

The aim in higher-risk disease is to modify the disease course and pursue the only curative option — allogeneic transplant in fit patients. The standard disease-modifying agent is a hypomethylating agent (HMA)azacitidine first-line — increasingly combined with the BCL-2 inhibitor venetoclax.[3][8]

Higher-risk MDS — hypomethylating agents and venetoclax

[1] [3] [8]

Higher-risk MDS — the curative pathway

  1. 1

    Confirm higher-risk disease — the high or very high IPSS-R (or IPSS-M) risk categories guide disease-modifying therapy.

  2. 2

    Assess transplant candidacy — allogeneic stem-cell transplant is the treatment with curative potential; therapy selection weighs comorbidities, fitness and transplant potential.

  3. 3

    If transplant-eligible: start an HMA (azacitidine 75 mg/m² for 7 days every 28 days) for disease control while donor search and work-up proceed.

  4. 4

    Proceed to allogeneic transplant — reduced-intensity conditioning makes transplantation feasible in patients aged 50 or over (systematic review: pooled one-year overall survival 65 percent, non-relapse mortality 26 percent).

  5. 5

    If transplant-ineligible: continue the HMA for as long as it works, plus best supportive care and clinical-trial enrolment.

  6. 6

    For multi-hit TP53 and therapy-related MDS: multi-hit TP53 is a top adverse genetic predictor in the IPSS-M — an HMA backbone plus a clinical trial.

[1] [3] [5] [13]

Allogeneic haematopoietic stem-cell transplant is the only potentially curative therapy. Selection balances transplant-related mortality against the poor natural history of untreated higher-risk disease — in a systematic review of reduced-intensity conditioning transplantation in patients aged 50 or over, pooled one-year overall survival was 65 percent and non-relapse mortality 26 percent. TP53-mutated and therapy-related MDS carry adverse risk (multi-hit TP53 is a top adverse genetic predictor in the IPSS-M), but fit selected patients are still transplanted, ideally within a clinical trial.[5][13]

The subtypes that bite

Isolated del(5q) — the 5q- syndrome

  • Macrocytic anaemia with or without thrombocytopenia, isolated del(5q), low blasts
  • One of the most favourable MDS subtypes
  • High response to lenalidomide 10 mg daily — transfusion independence in 67 percent (List, NEJM 2006)

MDS with ringed sideroblasts and SF3B1

  • SF3B1 mutation with ringed sideroblasts — favourable outcomes in the IPSS-M
  • Superior response to luspatercept in ESA-failed disease (MEDALIST: transfusion independence 38 versus 13 percent)

MDS with biallelic TP53 (MDS-biTP53)

  • Multi-hit TP53 — a top adverse genetic predictor in the IPSS-M
  • Frequent in therapy-related MDS; aggressive course
  • Very poor prognosis; HMA plus a clinical trial; transplant case-by-case

Therapy-related MDS (t-MDS)

  • MDS occurs more frequently in individuals with prior exposure to cytotoxic therapy
  • The IPSS-M applies to primary and to secondary or therapy-related MDS
  • Poor-risk biology; HMA backbone and selected transplant

Hypoplastic MDS

  • Hypocellular marrow mimicking aplastic anaemia
  • Distinguished from aplastic anaemia by dysplasia and a cytogenetic or molecular clone

Chronic myelomonocytic leukaemia (CMML)

  • An MDS/MPN overlap neoplasm — sustained peripheral monocytosis of 0.5×10⁹/L or more with monocytes at least 10 percent of leucocytes, under 20 percent blasts, and clonal evidence
  • Leukaemic transformation in about 15 to 20 percent over 3 to 5 years
  • Allogeneic transplant is the only treatment securing cure or long-term survival; otherwise hydroxycarbamide (hydroxyurea) and hypomethylating agents (DACOTA: decitabine versus hydroxycarbamide, similar overall survival)
[1] [4] [5] [6] [14]

When it goes wrong — complications and the traps that cost marks

Disease complications — progressive cytopenia (infection, bleeding, transfusion dependence), transfusional iron overload with end-organ damage (cirrhosis, cardiac failure, diabetes, hypogonadism, hypothyroidism), and transformation to AML in about 25 to 30 percent overall (higher in high-blast and TP53-mutated disease). Infection is the leading cause of death in MDS.[1]

Treatment complications — examiners test these by drug:[1]

Drug-specific toxicities in MDS therapy
Drug or modalityKey toxicityPractical action
Azacitidine or decitabine (HMA)Transient cytopenias, nausea, injection-site reactions, fatigue, infectionsAntiemetic, antimicrobial prophylaxis, transfusion support; monitor counts between cycles
Venetoclax (plus HMA)Tumour-lysis syndrome (ramp-up essential), neutropenia, GI upset, infectionsRamp-up the dose; hydration; allopurinol; monitor TLS labs and counts
LenalidomideNeutropenia, thrombocytopenia, rash, venous thromboembolism, teratogenicityMonitor counts; VTE prophylaxis; pregnancy prevention
DeferasiroxRenal and hepatic dysfunction, cytopenias, GI upset, rashMonitor creatinine, LFTs and ferritin; reduce or interrupt for toxicity
Erythropoiesis-stimulating agentsHypertension, thrombosis (small risk), pure red-cell aplasia (rare anti-EPO antibodies)Monitor blood pressure and haemoglobin; avoid in active malignancy where appropriate
Allogeneic SCTGraft-versus-host disease, overwhelming infection, organ toxicity, transplant-related mortalityGVHD prophylaxis (ciclosporin plus methotrexate or post-transplant cyclophosphamide); antimicrobial prophylaxis
[1]

The classic diagnostic pitfalls: mistaking B12, folate or copper deficiency (or alcohol) for MDS; overcalling reactive dysplasia (post-infection, growth-factor effect); failing to send cytogenetics and molecular testing on the marrow; not excluding HIV and other viruses; and diagnosing MDS from dysplasia alone without a persistent cytopenia or a clone. Treatment pitfalls: over-treating lower-risk disease like leukaemia; failing to chelate iron in the chronically transfused; delaying transplant referral for fit higher-risk patients; and using thrombopoietin-receptor agonists without monitoring blast progression.[1]

Prognosis and disposition

Prognosis is highly heterogeneous and driven by the risk score: the IPSS-R defines five prognostic categories and the IPSS-M six, and both discriminate overall survival, leukaemia-free survival and leukaemic transformation.[2][5]

Adverse prognostic factors: a higher marrow blast percentage, adverse or complex cytogenetics (especially -7, inv(3) and multi-hit TP53), a low haemoglobin, a low platelet count, a high LDH, older age and poor performance status. Favourable factors include isolated del(5q), an SF3B1 mutation, a normal karyotype, and a low blast count with limited transfusion need.[2]

Allogeneic stem-cell transplant is the only modality with curative potential, selected by age, comorbidity (HCT-CI), performance status and donor availability; the graft-versus-leukaemia effect is central to its efficacy. Follow-up is by serial full blood counts and transfusion requirement, periodic marrow with blast and cytogenetic reassessment, ferritin and iron monitoring, and surveillance for infection and treatment toxicity.[3]

Special populations

  • Younger patients — prioritise a donor search, germline (inherited-predisposition) testing (GATA2, RUNX1, ETV6, DDX41), and early allogeneic transplant referral; a younger patient with apparent "de novo" MDS always warrants a germline work-up before selecting a donor.[1]
  • Elderly and frail — supportive care, transfusion and iron chelation, with an HMA and reduced-intensity transplant reserved for fit higher-risk individuals selected by physiological rather than chronological age (a fit 72-year-old may be transplanted, a frail 60-year-old may not).[1]
  • Therapy-related MDS — poor-risk biology; discuss goals of care, an HMA and clinical trials; transplant selected case-by-case.
  • Inherited bone-marrow-failure syndromes (for example Fanconi anaemia) — a modified, fludarabine-based reduced-intensity protocol avoiding radiation, and donor or relative genetic screening to avoid using an affected relative.[1]
  • Resource-limited settings — transfusion, affordable HMA where available, and supportive antimicrobial prophylaxis; transplant access and novel-agent cost are major barriers, so access — not biology — often drives treatment choice.[1]
  • Pregnancy (very rare) — supportive care with transfusion; defer disease-modifying therapy; lenalidomide is absolutely contraindicated (teratogenic).[1]

The evidence and regional differences

The WHO 5th edition (2022) and the International Consensus Classification (ICC, 2022) both reorganise MDS around genetics, recognise MDS-biTP53 and the SF3B1 and del(5q) entities, and retain the 20 percent blast threshold for AML (the ICC defining AML by genetics at the 10 percent blast count for defining recurrent genetic abnormalities).[7]

The Revised IPSS (2012, Greenberg) remains the standard bedside risk tool, while the molecular IPSS-M (2022, Bernard) incorporates mutations (multi-hit TP53, FLT3, SF3B1 and others) to refine risk and restratify 46 percent of patients.[2][5]

Landmark trials and what they changed in MDS
Trial (authors, year)What it established
AZA-001 (Fenaux, Lancet Oncol 2009)Azacitidine 75 mg/m² daily for 7 days every 28 days improved median overall survival versus conventional care regimens in higher-risk MDS (24.5 versus 15.0 months) — established the HMA standard
MEDALIST (Fenaux, NEJM 2020)Luspatercept (1.0 up to 1.75 mg/kg every 3 weeks) achieved transfusion independence for 8 weeks or longer in 38 versus 13 percent of patients with lower-risk ringed-sideroblast MDS after ESA failure — first-in-class TGF-beta superfamily ligand trap
Lenalidomide in del(5q) (List, NEJM 2006)Lenalidomide 10 mg daily in del(5q) MDS: transfusion independence in 67 percent and cytogenetic improvement in 62 of 85 evaluable — disease-specific targeted therapy
VIALE-A (DiNardo, NEJM 2020)Azacitidine plus venetoclax (target dose 400 mg daily) improved median overall survival (14.7 versus 9.6 months) and complete remission in untreated AML ineligible for intensive therapy — BCL-2 inhibition added to HMA
IPSS-M (Bernard, NEJM Evidence 2022)Adding 31 gene mutations to the IPSS-R variables restratified 46 percent of patients into six risk categories — molecular risk stratification
[3] [4] [5] [6] [8]

Regional practice differs sharply by access. In high-income settings (NCCN — US; ESMO and ELN — Europe) there is routine availability of an HMA, luspatercept, lenalidomide, iron chelation and allogeneic transplant, with molecular NGS guiding therapy. In India and other low- and middle-income countries (ICMR context), care is largely transfusion- and HMA-based supportive therapy, with limited transplant and novel-agent access — cost, not biology, is the main determinant.

[1]

The mantra, and the mnemonics

What the IPSS-M adds

MDS-RISK

  • MMolecularthe IPSS-M layers 31 gene mutations onto the IPSS-R clinical variables
  • DDNA-methylationfounding hits TET2, DNMT3A, ASXL1 (shared with CHIP)
  • SSpliceosomeSF3B1 — ringed sideroblasts, favourable
  • RReclassifies46 percent of patients move risk category with the IPSS-M
  • IInactivationmulti-hit TP53 — the worst mutation, complex karyotype
  • SSixcategories — Very Low, Low, Moderate-Low, Moderate-High, High, Very High
  • KKaryotypecytogenetics still weighted; -7 and complex are adverse
[1]

The mantra: Dysplasia plus a cytopenia is MDS only when the mimics are excluded; 20 percent blasts is AML; lower-risk is supported, higher-risk gets an HMA and the only cure is a transplant — and copper deficiency is the great mimic.[1][3]

Ward-round test — three stems, thirty seconds each

Stem 1 — the man from the top of the topic (answer)Show

A 76-year-old with a macrocytic anaemia, a modestly reduced platelet count, hypogranular neutrophils and pseudo-Pelger-Huët cells on the film, normal B12, folate, copper and TSH, and no alcohol. What is the diagnosis, the next test, and how do you risk-stratify? Model: This is myelodysplastic syndrome — a macrocytic cytopenia with dysplastic morphology, the nutritional and toxic mimics excluded. The next test is a bone-marrow aspirate and trephine biopsy, with karyotype and molecular genetics as complementary studies that refine the diagnosis. Confirm the diagnostic triad (marrow dysplasia plus a persistent unexplained cytopenia plus exclusion of secondary causes) and check the blast percentage. Risk-stratify with the IPSS-R (cytogenetics, marrow blast percentage, depth of cytopenias) and, in a fit patient, the IPSS-M (adds mutations — multi-hit TP53, FLT3 and SF3B1 among 31 genes — restratifying 46 percent of patients). Lower-risk disease is supported with erythropoietin-based therapy when EPO is low and transfusion need small; higher-risk disease gets an HMA (azacitidine improved survival in AZA-001) and, if fit, an allogeneic transplant referral.[1][2][3][5][9]

Stem 2 — the cytopenia after gastric bypass (answer)Show

A 60-year-old woman two years after a Roux-en-Y gastric bypass has an anaemia and neutropenia with numb, tingling feet and an unsteady gait. The registrar books a bone-marrow biopsy for suspected MDS. What is the likely diagnosis, and what single test confirms it? Model: This is copper deficiency — malabsorptive bariatric surgery is a rapidly growing cause, classically producing anaemia and neutropenia with neurological manifestations (myelopathy, optic neuropathy). The single confirmatory test is a serum copper level. The haematological manifestations are rapidly reversible with copper replacement, but neurological improvement is often incomplete — many patients stabilise at best. Diagnosing it as MDS would expose the patient to a transplant work-up for a reversible nutritional deficiency. Always send B12, folate and copper before labelling dysplasia as MDS.[12]

Stem 3 — the fit 68-year-old with higher-risk MDS (answer)Show

A 68-year-old fit man has higher-risk MDS with increased marrow blasts, a normal karyotype, and molecular testing pending. What is the management plan, and what is the goal? Model: This is higher-risk MDS. The goal is to prolong survival and pursue the treatment with curative potential — allogeneic stem-cell transplant. Start an HMA (azacitidine 75 mg/m² for 7 days every 28 days — median overall survival 24.5 versus 15.0 months versus conventional care) for disease control while transplant assessment proceeds; the venetoclax–azacitidine combination improved survival in previously untreated AML and combination studies in MDS were under way. Send molecular testing — multi-hit TP53 is a top adverse genetic predictor in the IPSS-M. Proceed to allogeneic transplant with reduced-intensity conditioning, feasible in fit patients aged 50 or over. If transplant-ineligible, continue the HMA for as long as it works, with best supportive care. Throughout, give transfusion support and treat iron overload in the chronically transfused.[1][3][5][8][13]

References15Show
  1. [1]Garcia-Manero G Myelodysplastic syndromes: 2023 update on diagnosis, risk-stratification, and management Am J Hematol, 2023.PMID 37288607
  2. [2]Greenberg PL, Tuechler H, Schanz J, et al. Revised international prognostic scoring system for myelodysplastic syndromes Blood, 2012.PMID 22740453
  3. [3]Fenaux P, Mufti GJ, Hellstrom-Lindberg E, et al. Efficacy of azacitidine compared with that of conventional care regimens in the treatment of higher-risk myelodysplastic syndromes: a randomised, open-label, phase III study Lancet Oncol, 2009.PMID 19230772
  4. [4]Fenaux P, Platzbecker U, Mufti GJ, et al. Luspatercept in Patients with Lower-Risk Myelodysplastic Syndromes N Engl J Med, 2020.PMID 31914241
  5. [5]Bernard E, Tuechler H, Greenberg PL, et al. Molecular International Prognostic Scoring System for Myelodysplastic Syndromes NEJM Evid, 2022.PMID 38319256
  6. [6]List A, Dewald G, Bennett J, et al. Lenalidomide in the myelodysplastic syndrome with chromosome 5q deletion N Engl J Med, 2006.PMID 17021321
  7. [7]Khoury JD, Solary E, Abla O, et al. The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Myeloid and Histiocytic or Dendritic Neoplasms Leukemia, 2022.PMID 35732831
  8. [8]DiNardo CD, Jonas BA, Pullarkat V, et al. Azacitidine and Venetoclax in Previously Untreated Acute Myeloid Leukemia N Engl J Med, 2020.PMID 32786187
  9. [9]Hellström-Lindberg E, Gulbrandsen N, Lindberg G, et al. A validated decision model for treating the anaemia of myelodysplastic syndromes with erythropoietin + granulocyte colony-stimulating factor: significant effects on quality of life Br J Haematol, 2003.PMID 12648074
  10. [10]Platzbecker U, Symeonidis A, Oliva EN, et al. A phase 3 randomized placebo-controlled trial of darbepoetin alfa in patients with anemia and lower-risk myelodysplastic syndromes Leukemia, 2017.PMID 28626220
  11. [11]Angelucci E, Li J, Greenberg P, et al. Iron Chelation in Transfusion-Dependent Patients With Low- to Intermediate-1-Risk Myelodysplastic Syndromes: A Randomized Trial Ann Intern Med, 2020.PMID 32203980
  12. [12]Yarandi SS, Griffith DP, Sharma R, et al. Optic neuropathy, myelopathy, anemia, and neutropenia caused by acquired copper deficiency after gastric bypass surgery J Clin Gastroenterol, 2014.PMID 24583748
  13. [13]Zhang ZH, Lian XY, Yao DM, et al. Reduced intensity conditioning of allogeneic hematopoietic stem cell transplantation for myelodysplastic syndrome and acute myeloid leukemia in patients older than 50 years of age: a systematic review and meta-analysis J Cancer Res Clin Oncol, 2017.PMID 28470473
  14. [14]Patnaik MM, Tefferi A Chronic myelomonocytic leukemia: 2024 update on diagnosis, risk stratification and management Am J Hematol, 2024.PMID 38450850
  15. [15]Freifeld AG, Bow EJ, Sepkowitz KA, et al. Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: 2010 update by the infectious diseases society of america Clin Infect Dis, 2011.PMID 21258094
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