Juvenile myelomonocytic leukemia (JMML) is a rare type of leukemia that occurs in infants and toddlers, usually those under 2 years of age, and more often in boys. What are the causes and symptoms of juvenile myelomonocytic leukemia? What is the treatment?
Juvenile myelomonocytic leukemia(JMML) is a rare type of leukemia that occurs in infants and young children, usually those under 2 years of age, more often in boys.
Juvenile myelomonocytic leukemia belongs to the group of myelodysplastic / myeloproliferative neoplasms (MDS / MPN, myelodysplastic syndro-mes / myeloproliferative neoplasms), which also includes:
- chronic myelomonocytic leukemia (CMML)
- atypical chronic myeloid leukemia (aCML)
Juvenile Myelomonocytic Leukemia (JMML) - Causes
In 34 percent of cases there are mutations in the PTPN11 gene. These mutations are responsible for the development of Noonan syndrome, but in 1/3 of patients with JMML, despite mutations in the PTPN11 gene, this syndrome does not occur. In turn, 25 percent. cases there is an oncogenic mutation in the RAS gene.
Another 25 percent patients have type 1 neurofibromatosis (also known as neurofibromatosis type 1, NF1, Recklinghausen disease), which is caused by a mutation in the NF1 gene.
In addition, some patients may be diagnosed with monosomy (loss of one chromosome in a pair) of chromosome 7 or other abnormalities (e.g. trisomy 8 and 21, i.e. Down's syndrome).
These abnormalities lead to unrestrained multiplication of leukemia cells.
Juvenile myelomonocytic leukemia (JMML) - symptoms
The most common symptoms of JMML are:
U 10-15 percent patients may transform the disease into acute myeloid leukemia (AML)
- pallor
- fever
- signs of infection, e.g. bronchitis or tonsillitis
- symptoms of hemorrhagic diathesis on the skin (bruising under the skin or ecchymosis under the skin)
- cough
- spleen enlargement
- liver enlargement
- lymph nodes enlargement
Juvenile myelomonocytic leukemia, unlike acute myeloid leukemia (AML),rarely affects the central nervous system.
Juvenile Myelomonocytic Leukemia (JMML) - diagnosis
In order to diagnose the disease, peripheral blood counts (increased leukocytes, anemia and thrombocytopenia are found), bone marrow biopsy and genetic tests are performed.
During diagnosis, the physician should exclude leukemic reactions and other myeloid neoplasms, as well as infection with Epstein-Barr virus, cytomegalovirus, human herpes virus 6 and parvovirus B19.
It should be noted, however, that identifying these infections does not preclude the recognition of JMML.
Juvenile myelomonocytic leukemia (JMML) - treatment
The only proven effective treatment for JMML patients is hematopoietic cell transplantation. It should be performed as soon as possible after the diagnosis.
No pre-transplant treatment has been proven effective, but chemotherapy should be considered in children with more progressive disease.
Juvenile myelomonocytic leukemia (JMML) - prognosis
The median survival time of patients who have not undergone a hematopoietic cell transplant is approximately 12 months.
Patients mainly die from respiratory failure caused by leukemia cells infiltrating the lung tissue.
Pediatric oncology and hematology , under. ed. Chybicka A., Sawicz Birkowska K., PZWL Medical Publishing, Warsaw 2008