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216 / Chapter 16 Myelodysplasia

In most cases, the disease is primary but in a
Table 16.2 Cytogenetic abnormalities in

significant proportion of patients it is secondary to
myelodysplastic syndromes.
chemotherapy and/or radiotherapy that has been
given for treatment of another malignancy. Th is 1 Chromosome deletion or loss (e.g. del 5q,

latter type is termed therapy - related MDS (t - monosomy 5, del 7q. monosomy 7, del 11q)

MDS) and is now classified with therapy - related

2 Chromosome gain (e.g. trisomy 8, trisomy 11)
AML.

Th e pathogenesis of myelodysplastic syndromes 3 Chromosome rearrangement (e.g. t3q26,
(MDS) is unclear but is presumed to start following t(1; 7), t11q23)
genetic damage to a multipotent haemopoietic pro- 4 Complex karyotypes: three or more

genitor cell. The immune system may have a minor abnormalities
role in suppressing bone marrow function and
immunosuppression is sometimes used in treatment
(see below).
Table 16.3 Classifi cation of risk group in

myelodysplastic syndromes (MDS).
Classifi cation Lower risk MDS Higher risk MDS

The myelodysplastic syndromes are classified on the Survival of 3 – 10 years Survival < 1.5 years

basis of the blood count, their morphological
Low rate of transformation High rate of AML
appearance, the number of blast cells in blood or to AML transformation
bone marrow and cytogenetics (Table 16.1 ).

Although the classification appears complex, the RA, RARS RAEB
principles are as follow: RCUD, RCMD
• Dysplasia may be present solely in a single lineage MDS - U, MDS del(5q)
– red cells ( refractory anaemia ), neutrophils or IPSS low IPSS high
platelets – or present in two or more myeloid
lineages ( refractory cytopenia with multilineage dys-
AML, acute myeloid leukaemia; IPSS, International
plasia ; RCMD). Prognostic Scoring System; RA, refractory anaemia;
• Erythroid dysplasia can also be associated with RAEB, refractory anaemia with excess blasts; RARS,
refractory anaemia with ring sideroblasts; RCUD, refractory

ring sideroblasts to define a unique subtype. Th e
cytopenia with unilineage dysplasia; RCMD, refractory
definition of a pathological ring sideroblast is cytopenia with multilineage dysplasia; MDS, myelodys-

an erythroid precursor with five or more iron plastic syndrome; MDS - U, myelodysplastic syndrome,

unclassifi able.
granules encircling at least one - third of the
nucleus. A rare condition, refractory anaemia
with ring sideroblasts and thrombocytosis (plate-
9
lets > 450 × 10 /L) in which the JAKV617F thrombocytosis in 50% of cases. It has a particu-
mutation is often present, is classifi ed with larly good prognosis (Table 16.3 ).
the myelodysplastic – myeloproliferative diseases
(Table 16.4 ).
Clinical f eatures
• If the blast cell count is increased in blood or

bone marrow, the diagnosis is made of refractory Th e disease has an incidence of 4 in 100 000 and a
anaemia with excess blasts and these subtypes have slight male predominance. Over half of patients are
a poor prognosis. over 70 years and fewer than 25% are less than 50
• 5q - Syndrome receives its own classifi cation. Th e years old. Th e evolution is often slow and the disease
gene that is deleted is RPS14 , encoding a ribos- may be found by chance when a patient has a blood
omal protein (see Fig. 22.3 ). It is more common count for some unrelated reason. Th e symptoms, if
in women and typically there is anaemia with present, are those of anaemia, infections or of easy