This is a diagnostic prospective multicenter study. This study will be conducted in 32 centers of the Société Française des Cancers et Leucémies de l'Enfants et de l'Adolescent (SCFE) in patients with non-Hodgkin lymphoma and treated according to recommendations of the SFCE for each type of non-Hodgkin lymphoma. All patients will have a PET / CT associated with conventional imaging time of remission assessment. Histological examination of residual tumor will be conducted whenever practicable in patients with pathologic residual image on conventional imaging and / or PET / CT. A central review of conventional imaging examinations and PET / CT will be performed independently from each other.

Moreover, whenever possible, patients will have a PET / CT at diagnosis and an early PET / CT (between J8 and J28 according to the type of lymphoma and toxicities due to treatment). The results of the early PET / CT should not lead to treatment modifications.

In case of residual tumor at remission assessment, therapeutics changes as recommended therapeutic protocols will be based on histologic findings and not on the results of PET / CT alone.

Inclusion Criteria:

1. All cases of NHL corresponding to one of the following histologies:

   • Burkitt and Burkitt-like (LB)
   • Large cell B-cell lymphoma (LBGC)
   • Primary mediastinal B cell lymphoma (LBPM)
   • Lymphoblastic lymphoma (LL)
   • Anaplastic large cell lymphoma (ALCL)

2. Age > 2 years and < 21 years

3. Treated in a SFCE protocol

4. Treated in a center with the possibility of organizing a PET / CT at the time of remission assessment

5. Affiliation to a social security system

6. Possible follow-up for at least 2 years

7. written informed consent signed by the parents or parental authority or the patient himself if he is over 18 years

Exclusion Criteria:

1. relapsing patients
2. Patients with absolute cons-indications to the achievement of a PET scan: pregnancy, incontinence, poorly controlled diabetes or blood glucose> 10 mmol/l, alterations of superior functions or claustrophobia, making the test impossible.
3. pre-existing or evolving infectious inflammatory disease making PET / CT difficult to interpret