Study of the Medullary Microenvironment in Acute Childhood Leukemia

Inclusion Criteria: * for patients with AL: 1. Child with acute lymphoblastic or myeloblastic leukemia at diagnosis 2. Not having received prior hematological treatment 3. Aged 1 to 15 years old 4. Whose 2 parents, or the holder of parental authority, have signed a consent enlightened. 5. Affiliated patient or beneficiary of a social security scheme. * Control group patients: 1. Child undergoing orthopedic surgery exposing the bone marrow (osteotomy of the pelvis). 2. Aged between 1 and 15 years old. 3. Having no pathology of hematological origin. 4. Not having received any treatment that could interfere with the functioning of the bone marrow. 5. Whose 2 parents or the holder of parental authority have signed a consent enlightened. 6. Affiliated patient or beneficiary of a social security scheme. Exclusion Criteria: * for patients with AL: 1. Patient under 1 year old and over 15 years old. 2. Contraindication to myelogram. 3. Absence of signature of the informed consent by the 2 parents or the holder of parental authority. 4. Patients with relapsed acute lymphoblastic or myeloblastic leukemia. 5. Having received prior hematological treatments. 6. Parents with physical or mental condition not allowing to understand the informed consent. * Control group patients 1. Patient under 1 year old and over 15 years old. 2. Having an underlying haematological pathology. 3. Absence of signature of the informed consent by the 2 parents or the holder of parental authority. 4. Having received prior hematological treatments. 5. Parents with physical or mental condition not allowing to understand informed consent.