Juvenile Myelomonocytic Leukemia (JMML)
Introduction
Clonal hematopoietic disorder which affects children. It is characterised by
granulocytic and monocytic proliferation.
Etiology
25% monosomy 7, 35% mutation of PTPN11, 20% mutation of
NRAS, KRAS2 and NF1, BCR-ABL1 is absent.
Clinical signs
- frequent infections
- hepatosplenomegaly
- lymphadenopathy or tonsil swelling in approximately 50% of cases
- leukocytosis in peripheral blood usually 20 – 30×109/l
with monocytosis, BCR/ABL negative, less than 20% blasts
in peripheral blood or bone marrow, predominant granulopoietic proliferation in bone marrow,
less significant increase of the monocyte count,
dysplastic changes are often only minimal
- prognosis: without allogeneic stem cell transplantation, the
median survival time is approximately 1 year, progression into AML is rare
