Intergroup Trial for Children or Adolescents With Primary Mediastinal Large B-Cell Lymphoma: DA-EPOCH-Rituximab Evaluation

Inclusion Criteria: * Histologically proven Primary Mediastinal Large B-Cell Lymphoma (PMLBL). * PMLBL without central nervous system (CNS) involvement. * 6 months to less than 18 years of age at the time of consent. * Males and females of reproductive potential must agree to use an effective contraceptive method during the treatment, and after the end of treatment: during twelve months for women, taking into account the characteristics of rituximab * Complete initial work-up within 8 days prior to treatment that allows definite staging. * Able to comply with scheduled follow-up and with management of toxicity. * Signed informed consent from patients and/or their parents or legal guardians Exclusion Criteria: * Follicular lymphoma, mucosa-associated lymphoid tissue (MALT) and nodular marginal zone * PMLBL patients with CNS involvement * Patients with congenital immunodeficiency, chromosomal breakage syndrome, prior organ transplantation, previous malignancy of any type, or known positive HIV serology. * Evidence of pregnancy or lactation period. * There will be no exclusion criteria based on organ function. * Past or current anti-cancer treatment except corticosteroids during less than one week. * Tumor cell negative for CD20 * Prior exposure to rituximab. * Severe active viral infection, especially hepatitis B. * Hepatitis B carrier status history of hepatitis B virus (HBV) or positive serology. * Participation in another investigational drug clinical trial. * Patients who, for any reason, are not able to comply with the national legislation.