Lymphoproliferative disorders (LPD) are a major cause of morbidity and mortality in immunodeficient patients. There have been isolated case reports of patients with childhood ALL who developed LPD after ALL diagnosis, without undergoing stem cell transplantation, but data regarding such cases are limited. We propose here an international collaboration, to form a comprehensive database of children who developed LPD after diagnosis of acute lymphoblastic leukemia/lymphoma

Lymphoproliferative disorders (LPD) are a major cause of morbidity and mortality in immunodeficient patients. These disorders have been extensively described in the post-transplant setting, ie after hematopoietic stem cell (SCT) or solid organ (SOT) transplant. However, since the 1980's, there have been isolated case reports of patients with childhood ALL, who developed LPD after diagnosis of ALL, without undergoing SCT. Comprehensive information is unavailable regarding the prevalence, clinical manifestations, treatment, outcome and pathogenesis of such disorders in this setting. We propose here an international collaboration, to form a comprehensive database of children who developed LPD during the treatment of acute lymphoblastic leukemia/lymphoma (ALL/LBL).

Information will be collected in a de-identified fashion regarding patient characteristics, leukemia and LPD characteristics, treatment and outcome. The aims of this retrospective study are:

1. To build a database of children who developed LPD after diagnosis of ALL/LBL
2. To investigate the characteristics and outcome of this disorder

Inclusion Criteria:

• Children and young adults treated for acute lymphoblasticleukemia/lymphoma who developed LPD after ALL/LBL diagnosis

Exclusion Criteria:

• age>30 years

Children and young adults (<30 years of age), previously diagnosed with acute lymphoblastic leukemia/lymphoma, who developed LPD after ALL/LBL diagnosis