This document discusses Myelodysplastic Syndromes (MDS), including definitions, classification systems, predisposing factors, cytogenetic abnormalities, theories of pathophysiology, clinical manifestations, laboratory/pathology findings, and morphological abnormalities. Key points: - MDS are clonal stem cell disorders characterized by ineffective hematopoiesis leading to cytopenias from defects in maturation. There have been many historical names and classification schemes, now defined by WHO. - Predisposing factors include aging, genetic syndromes, chemotherapy/radiation, and environmental exposures. Cytogenetic abnormalities impact prognosis. - Pathophysiology involves genetic/epigenetic changes, telomere dysfunction, altered micro

1. Dr. Indranil Bhattacharya
MD & WHO Fellow (Pathology)
HOD – Dept. of Pathology
Jagjivan Ram Hospital
Mumbai
Myelodysplastic Syndromes

2. Definition:
MDSs are clonal disorders of the
hematopoietic stem cell characterized by
ineffective hematopoiesis leading to
peripheral blood cytopenias, reflecting
defects in erythroid, myeloid and
megakaryocytic maturation and by frequent
evolution to AML.

3. Different Terminology of MDS
 Refractory anemia 1938 Rhoades and Barker
 Preleukemic anemia 1949 Hamilton-Paterson
 Preleukemia 1953 Block et al.
 Refractory anemia with ringed sideroblasts 1956 Bjorkman
 Refractory normoblastic anemia 1959 Dacie et al
 Smoldering acute leukemia 1963 Rheingold et al
 Chronic erythremic myelosis 1969 Dameshek
 Preleukemic syndrome 1973 Saarni and Linman
 Subacute myelomonocytic leukemia 1974 Sexauer et al
 Chronic myelomonocytic leukemia 1974 Miescher and Farguet
 Hypoplastic acute myelogenous leukemia 1975 Beard et al
 Refractory anemia with excess myeloblasts 1976 Dreyfus
 Hematopoietic dysplasia 1978 Linman and Bagby
 Subacute myeloid leukemia 1979 Cohen et al
 Dysmyelopoietic syndrome 1980 Streuli et al
 Myelodysplastic syndromes 1982 Bennet et al

4. Predisposing Factors
Heritable predisposition
Constitutional genetic disorders
Down syndrome, Trisomy 8 mosaicism
Familial monosomy 7
Neurofibromatosis 1
Germ cell tumors (embryonal dysgenesis)
DNA repair deficiencies
Fanconi anemia, Ataxia telangiectasia, Bloom syndrome
Xeroderma pigmentosum

5. Predisposing factors…..
Acquired:
Senescence
Mutagen exposure
Genotoxic therapy
Alkylators
ß-emitters (phosphorus-32)
Autologous bone marrow transplantation
Environmental or occupational exposure (e.g., benzene)
Tobacco

6. Cytogenetic Abnormalities in
Myelodysplastic Syndromes
Prognosis Alteration
Intermediate Trisomy 8
Favorable 5q-, 20q-, 12p-
Unfavorable i(17q ) or t(17p), inv(3),
translocation (3;3), complex (at
least 3 anomalies)

7. Theories of
Pathophysiology
involved
in MDS Development
Potential Targets/
Components
Involved
Overall Result of Abnormality
Environmental / Aging
Aging Increased BM
apoptosis
Decreased hematopoietic stem cell
pool
Environmental
Exposures
Smoking
Radiation
Benzene
Viral Infections
Chemotherapy
Direct Toxicity to hematopoietic
stem cells.
Telomere Abnormalities Potential decreased
telomerase and
subsequent
telomere shortening
•Impaired ability to renew stem cell
pool.
•Genetic Instability

8. Genetic
Alterations
Potential Targets/
Components Involved
Overall Result of Abnormality
Cytogenetic
Abnormalities
Common Abnormalities:
• 5q- , 20q-
• Y- , Trisomy 8
• 7q-/Monosomy7, 17p
Syndrome
• 11q23, 3q
• p53 mutations, Ras mutations
• Complex Cytogenetics
• Abnormalities: typically
unbalanced genetic loss
• Numerous theories of tumor
suppressor Loss
• Multi-Hit progression from low
risk MDS to AML
• Genetic Instability
Epigenetic
Modulation
•Hypermethylation
•Acetylation Alterations
Methylation and acetylation
abnormalities lead to silencing of
genes important in cell cycle,
differentiation, apoptosis,
angiogenesis

9. Altered Bone Marrow
Microenvironment
Components
Involved
Overall Result of Abnormality
Altered Bone Marrow
Microenvironment
Cytokines
Up regulation of:
TNF-, IFN-gamma,
TGF-Beta, IL-1B, IL-6,
Il-11
• Alteration of growth,
differentiation, angiogenesis
• Immune modulation
Alterations in Apoptosis
via Signalling
• Increased TNF-
levels
• FAS: Increased
Apoptosis
• BCL-2 alterations
• Increased apoptosis and
proliferation in early stage MDS
leading to hypercellular marrow
with peripheral cytopenias
• Decreased apoptosis and
increased proliferation in later
stage MDS leading to progression
to AML
Increased
Angiogenesis
• Increased VEG-F
• Possible Increase:
gFGF and EGF
Angiogenin
Increased Microvessel Density
(MVD): role in pathogenesis not
clearly elucidated but associated
with progression to AML

10. Altered Bone Marrow
Microenvironment
Components Involved Overall Result of
Abnormality
Immune Dysregulation • T cell Expansion
• B cell alterations
• Increased T cells leading to
potential attack on
hematopoietic stem cells.
• Etiology: Possible chronic
antigenic stimulation
Abnormal Differentiation • Cell Cycle Maturation
arrest.
• Altered Proliferation.
• Transcription Factors
alterations
• Impaired maturation
• Cytopenias
• Progression to leukaemia

13. FAB Classification of MDS
FAB Subtype Peripheral smear Bone Marrow
Refractory anemia
(RA)
Anaemia, Blasts< 1%,
Monocytes <1x109 /L
Blasts< 5%, ringed siderblasts
< 15% of erythroblasts
Refractory anemia
with Ringed
sideroblasts
(RARS)
Anaemia, Blasts< 1%,
Monocytes <1x109 /L
Blasts< 5%, ringed siderblasts
> than 15% of erythroblasts
Refractory anemia
with excess blasts
(RAEB)
Anaemia, Blasts>1%,
Monocytes <1x109 /L
OR
Blasts <5%
Blasts 5%
BUT
Blasts20%

14. FAB Subtype Peripheral
smear
Bone Marrow
Refractory Anemia with
Excess Blasts in
Transformation (RAEB-T)
Anaemia, Blasts 5%
OR present Auer rods
Blasts 20-29%
OR present Auer rods
CMML Monocytes>1x109 /L,
Granulocytes often
increased, Blasts
<5%.
Blasts upto 20%,
Promonocytes often
increased.

15. WHO Classification of MDS

16. Subtype Blood Bone Marrow
Refractory
Anaemia (RA, RN,
RT)/RCUD
Single or bicytopenia,
no blasts
Unilineage dysplasia 10% of
the cells in one myeloid lineage,
< 5% blasts, <15% ringed
sideroblasts
Refractory
Anaemia with
Ring Sideroblasts
(RARS)
Anaemia, no blasts Erythroid dysplasia only, < 5%
blasts, 15% ringed
sideroblasts
Refractory
Cytopenia with
Multilineage
Dysplasia
(RCMD)
Cytopenia(s), no or
rare blasts (<1%), no
Auer rods, < 1 x 109/L
monocytes
Dysplasia in 10% of cells in 2
or more hematopoietic lineages,
<15% ring sideroblasts, < 5%
blasts, no Auer rods.
RCMD and
Ringed
Sideroblasts
(RCMD-RS)
Cytopenias (bi or
pancytopenia), No or
rare blasts, No Auer
rods, < 1 x 109/L
monocytes
Dysplasia in  10% of cells in 2
or more myeloid cell lines, < 5%
blasts, 15% ringed
sideroblasts, No Auer rods

17. Subtype Blood Bone Marrow
Refractory anemia
with excess blasts-1
(RAEB-1)
Cytopenias,< 5%
blasts
No Auer rods, < 1 x
109/L monocytes
Unilineage or multilineage
dysplasia, no Auer rods,
5-9% blasts
Refractory anemia
with excess blasts-2
(RAEB-2)
Cytopenias, 5-19%
blasts, Auer rods ±, <
1 x 109/L monocytes
Unilineage or multilineage
dysplasia, Auer rods ±, 10-
19% blasts
MDS, unclassified
(MDS-U)
Cytopenia(s), No or
rare blasts (<1%), No
Auer rods
Unilineage dysplasia in
granulocytes or
Megakaryocytes, < 5%
blasts, No Auer rods
MDS associated with
isolated del(5q)
Anemia, < 1% blasts,
platelets normal or
increased
Normal to increased
megakaryocytes with
hypolobated nuclei, < 5%
blasts, No Auer rods Isolated
del(5q)

18. Myelodysplastic/Myeloprolifierative Neoplasms
(MDS/MPN) WHO Classification

19. Myelodysplastic/Myeloprolifierative Neoplasms
(MDS/MPN) WHO Classification
Subtype Blood Bone Marrow
CMML-1 > 1 x 10/L monocytes, < 5%
blasts 9
Dysplasia in 1 hematopoietic
line, < 10% blasts
CMML-2 > 1 x 10 /L monocytes, 5%-
19% blasts or Auer rods
Dysplasia in  1 hematopoietic
line, 10%-19% blasts, or Auer
rods
Atypical chronic
myeloid leukemia
(CML), Bcr-Abl 1
negative
WBC 13 x 10 /L, neutrophil
precursors > 10%, < 20%
blasts
Hypercellular, < 20% blasts
Juvenile
myelomonocytic
leukemia (JMML)
> 1 x 10/L monocytes, <
20% blasts
> 1 x 10 /L monocytes, < 20%
blasts
MDS/MPN,
unclassifiable
('Overlap syndrome')
Dysplasia +
myeloproliferative features,
no prior MDS or MPN
Dysplasia + myeloproliferative
features

20. Changes made by WHO classification
 The criteria for the diagnosis of AML was altered
(20% blasts).
 RAEB -T------ RAEB-II category.
 Problem relating to the classification of CMML/a
CML was resolved by creation of MDS/MPD
category to which both were assigned together with
other cases with features overlapping between
MDS/MPD.

21. Drawback of WHO classification
 They incorporate very little cytogenetic and molecular
genetic information.
 Only the 5q- syndrome is defined.

22. Clinical manifestations
 The symptoms experienced by patients with MDS
are related to the type and severity of the peripheral
blood cytopenias.
 Symptoms:
o Fatigue,
o decreased exercise tolerance,
o bleeding,
o easy bruisability, or recurrent bacterial infections.

23. Physical examination
• Pallor
• Peripheral oedema
• Evidence of heart failure (severe anaemia).
• Petechiae on the lower extremities or on the buccal mucosa
(if severe thrombocytopenia is present).
• Splenomegaly may be present, especially in patients with
chronic myelomonocytic leukemia (CMML).

24. Laboratory tests
 Decrease of one peripheral blood count or multiple
cytopenias.
 Anaemia- Microcytic/normocytic/macrocytic.
 Reticulocytopenic (corrected reticulocyte count <1%).
 Leukopenia due to a decrease in the absolute neutrophil
count
 Leukoerythroblastic picture.
 An absolute monocytosis (monocytes >1000/μL) is present
in CMML.
 Thrombocytopenia may be present
 Thrombocytosis {Refractory Anaemia (RA) and an isolated
5q− abnormality, or in some cases of RARS}.

25. Bone marrow
 Essential to diagnose MDS.
 The BM trephine biopsy provides better assessment of
marrow cellularity and is required to evaluate the
existence of fibrosis. Abnormal distribution of cells is
detectable.
 The bone marrow biopsy usually is hypercellular for the
age of the patient.
 However, approx 15% of patients have a hypocellular
marrow (cellularity <25%).

26. Bone marrow..…
 Granulocytic precurosrs may be clustered centrally
rather than showing their normal paratrabecular
distribution.
 This phenomenon has been designated as abnormal
localization of immature precurors (ALIP).
 ALIPs are diagnostically important if they are detected
in since their presence confirms MDS rather than a
secondary anaemia.
 Use of antiglycophorin antibody highlights the presence
of clusters of immature erythroid cells and helps to
distinguish from ALIPs.

27. Bone marrow ..…
 Abnormal megakaryocytes are readily assessed.
 Megakaryocytes may be clustered or found in
paratrabecular position.
 Apoptosis is increased.
 Nonspecific abnormalities - increased macrophages,
prominent mast cells, lymphoid follicles and plasma cell
aggregates.

28. BM trephine biopsy section, RAEB-T, showing increased numbers of blasts
forming a small cluster (centre) (an abnormal localization of immature
precursors or ALIP).

29. Cytochemical Reactions
 Most important and essential - Perl’s stain for iron.
 Sudan Black B and MPO - Ensure that all cases
with Auer rods are recognized and classified as
RAEB-T (FAB) or RAEB-2 (WHO).
 In CMML - Non Specific Estarage (NSE) is
necessary to identify monocyte component in bone
marrow.
 PAS - Erythroblasts

30. Morphological abnormalities in MDSs

31. Erythroid
 PS Bone marrow
 Ovalomacrocytes Megaloblastoid erythropoiesis
 Elliptocytes Nuclear budding
 Acanthocytes Ringed sideroblasts
 Stomatocytes Internuclear bridging
 Teardrops Karyorrhexis
 Nucleated erythrocytes Nuclear fragments
 Basophilic stippling Cytoplasmic vacuolization
 Howell-Jolly bodies Multinucleation
Ring sideroblasts

32. Myeloid
 PS Bone marrow
 Pseudo–Pelger-Huet anomaly Defective granulation.
 Auer rods Maturation arrest at
myelocyte stage.
 Hypogranulation Increase in monocytoid
forms.
 Nuclear sticks Abnormal localization of
immature precursors.
 Hypersegmentation
 Ring-shaped nuclei
 Pseudo- Chediak Higashi granules

33. Megakaryocyte
 PS Bone marrow
 Giant platelets Micromegakaryocytes
 Hypogranular or agranular Hypogranulation
Platelets Multiple small nuclei

34. PB film, MDS, showing anisocytosis, poikilocytosis and two pseudo-Pelger–
Huët neutrophils, one of which is also hypogranular.

35. Refractory cytopenia with multilineage dysplasia (RCMD). Bone marrow aspirate
(Wright–Giemsa stain – 100x). Erythroid precursors with nuclear irregularity and
myeloid precursors with hypogranulation and hyposegmentation

36. Internuclear bridging

37. Dysrythropoietic changes - nuclear budding, karyohexxis

38. A) Leishman Stain (×100 magnification). Showing dyserythropoiesis.
B) May–Grunwald Giemsa Stain (×100 magnification). Arrow showing
binucleate erythroblast. C) Leishman Stain (×200 magnification).
Showing multinucleate erythroblast and erythroid dysplasia

39. REFRACTORY CYTOPENIA WITH MULTILINEAGE DYSPLASIA: Dysplastic
erythroid precursor with multi-nucleation and nuclear fragments (arrow) and
dysplastic myeloid precursor with both eosinophilic and basophilic granulation
(arrowhead)

40. Bone marrow biopsy shows
uniformly small and monolobated
megakaryocytes (arrows).

41. BM aspirate, RA, showing a binucleate micromegakaryocyte which is budding
platelets

42. Dysplasia in myeloid precursors can be manifested by dysplastic
granulation with granules of eosinophilic type and basophilic type (arrow)

43. Abnormal nuclear lobation such as seen in this myelocyte with two nuclei (long
arrow), abnormal distribution of granules causing granular polarity (arrowhead),
and mixed eosinophilic and basophilic granulation (top arrow)

44. Neutrophils with ring-like nuclei (ringed-neutrophil, arrow), A megaloblastoid
erythroid precursor is also seen (arrowhead)

45. Refractory anaemia, RCUD, RN, RT (WHO)
 10-20% of MDS.
 Older adults, median age- 65-70years.
 PS-
 Anaemia, marked anisocytosis, poikilocytosis.
 Normochromic, normocytic/macrocytic,
occasional hypochromia.
 Blasts are uncommon, less than 1%.

46. Refractory anaemia with ring sideroblasts
(WHO)………
 Bone marrow shows erythroid hyperplasia.
 Myeloblasts are <5% of BM nucleated cells.
 15% or more of red cell precursors are ring
sideroblasts.
 Iron laden macrophages may be prominent.
 Very low rate of evolution to AML.

47. BM aspirate, RARS, showing numerous ring sideroblasts, several of which
can be seen to have defectively haemoglobinized cytoplasm. Perls’ stain

48. Refractory anaemia with excess of
blasts-2
 It is categorized as RAEB-2 if bone marrow blasts
are 10-19%, if the peripheral blood blasts are 5-
19% (regardless of bone marrow blast count) or if
Auer rods are present.
 Dysplasia in at least 10% of cells of one or more
myeloid lineages.
 More than a third patient suffered transformation
to AML.
 Median survival poor than RAEB-1.

49. BM trephine biopsy section from a patient with hypoplastic MDS (RAEB)
showing: (a) a disorganized marrow of low cellularity

50. Evolution of MDS
 Patients with MDS may die of marrow failure as a direct
consequence of MDS or may die following
transformation to acute leukemia.
 Myelodysplastic syndromes may evolve into other
MDS.
 Change is usually into a worse prognostic category and
very rarely into favorable.
 Thus RA and RARS may evolve into either CMML.

51. Evolution of MDS…..
 Variation in number of monocytes can alter
classification, mainly between CMML and RAEB and
rarely ring sideroblasts disappear so that RARS
converts to RA.
 When acute leukemia supervenes it may develop
within a brief period or there may be stepwise
evolution over weeks and months.
 Acute leukemia that occurs in MDS is always AML,
but rare cases of ALL and bilineage/ biphenotypic
leukemia have been reported.

52. Algorithm of MDS diagnosis

53. Has there been exposure to cytotoxic drugs or
radiation
No
Are there 5-19% blast cells in the blood or 10-19%
blast cells in the bone marrow or Auer rods
Are there no more than 5% blasts cells in the
blood and 5-9% in the bone marrow
No
No
Is there an isloated 5q-
No
Is there multilineage dysplasia
No
RA or RARS
Yes
Therapy related MDS
Yes
RAEB-II
Yes
RAEB-I
Yes
5q- syndrome
Yes
RCMD