Page 235 - Essential Haematology

Chapter 16 Myelodysplasia / 221

a complete remission being first obtained with plasia in other lineages and negative for the BCR -
chemotherapy, although in high - risk cases initial ABL1 translocation. The total white cell count is

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chemotherapy may be tried to reduce the blast pro- usually raised and may exceed 100 × 10 /L. Patients

portion and the risk of recurrence of the MDS. may develop skin rashes and around half have
splenomegaly. Bruising is frequent and gum hyper-
General s upport c are o nly trophy and lymphadenopathy may also be present.
This is most suitable in elderly patients with other TET - 2 mutations are frequent. Treatment is diffi -

major medical problems. Transfusions of red cells cult although oral hydroxyurea or etoposide may be
and platelets, and therapy with antibiotics and anti- useful. SCT may be tried in younger patients.
fungals, are given as needed. Median survival is approximately 2 years, with
increased marrow blasts a predictor of poor outcome.
Myelodysplastic/ m yeloproliferative
n eoplasms Atypical c hronic m yeloid l eukaemia

A group of disorders are classified between myelo- These patients have an increased white cell count

dysplasia and myeloproliferative disorders as they with mainly granulocytes and granulocyte precur-
show the presence of dysplastic features but also sors in the blood and hypercellular bone marrow
increased number of circulating cells in one or more but the Philadelphia chromosome and BCR - ABL1

lineage (Table 16.4 ). There are some common clini- fusion gene are not present. There are usually some

cal and genetic features between these disorders. morphological features in the blood or bone marrow
Mutations of the TET2 tumour suppressor gene on of myelodysplasia. Treatment is diffi cult and the
chromosome 4 are found in about 20% of cases, outlook is poor.
and of JAK2 in a smaller proportion.
Juvenile m yelomonocytic l eukaemia
Chronic m yelomonocytic l eukaemia
This presents in the first 4 years of life and has

This is defined by a persistent monocytosis of features of both myelodysplasia and a myeloprolif-

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> 1.0 × 10 /L with blasts < 20% in the marrow, dys- erative disease. There is often an eczematous, skin
Table 16.4 Classifi cation of myelodysplastic/myeloproliferative neoplasms.

Diagnostic features
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Chronic myelomonocytic Monocytosis > 1 × 10 /L
leukaemia
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Atypical chronic myeloid WBC > 13 × 10 /L

leukaemia BCR - ABL1 absent
BCR - ABL1 negative
Juvenile myelomonocytic
leukaemia
Myelodysplastic/
myeloproliferative
neoplasm, unclassifi able
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Refractory anaemia with ring Platelet count > 450 × 10 /L
sideroblasts associated Large atypical megakaryocytes
with marked
thrombocytosis