Juvenile myelomonocytic leukaemia (JMML)

Juvenile Myelomonocytic Leukaemia (JMML)


Juvenile myelomonocytic leukaemia (JMML) is a very rare type of slowly developing (chronic) blood cancer that occurs in young children.

Leukaemia means a cancer of the blood forming system.

The blood forming system is the bone marrow, the soft inner part of your bones.


Although JMML has leukaemia as part of its name, the World Health Organisation (WHO) does not classify it as a leukaemia. It’s now included in a group of blood cancers called myeloproliferative and myelodysplastic disorders.


Symptoms of JMML

JMML is rare. And it develops slowly. This means that symptoms might develop over weeks or months.

In JMML, as the abnormal blood cells multiply in the bone marrow, fewer normal blood cells are made.

If there are not enough normal blood cells, the body cannot work normally.

Symptoms include nosebleeds and bleeding gums, looking pale, fever, being tired, lethargic and generally feeling unwell, being irritable – it might take a young child longer to settle, bruising easily, getting lots of infections, an enlarged liver and spleen – you might have noticed your child has jumped a nappy or trouser size quickly, pain in the tummy – if the monocytes have collected in this area, skin rashes, cough and wheezing.


For further guidance about Juvenile myelomonocytic leukaemia (JMML), speak to your General Practitioner.