This free journal suppl. entitled: Special Issue: Fifth International Symposium on Childhood, Adolescent and Young Adult Non-Hodgkin Lymphoma Abstracts, 22 October 2015, Varese, Italy ; Peer-reviewed Oral Presentation ; BACKGROUND: Non-anaplastic peripheral T-cell lymphomas (PTCL) are rare in the pediatric population and little is known about outcome and treatment options. OBJECTIVES: The present study is a joint, international, retrospective review of reported cases of PTCL in patients below 18 years, with focus on treatment options and outcome. Design/Methods: Only cases reviewed by national or international reference pathologists have been included. RESULTS: Until now, 122 patients diagnosed between 1995 and 2015 have been included in the study. The frequency of PTCL in the population-based reports (western Europe) was around 1%, which is lower than reported in older publications where Alk+ ALCL were included in this group. Patients were treated according to different treatment regimens, classified as B-cell type, T-cell type or other. pOS at 5 years for the group was at 54% and pEFS at 45%. 28 patients were reported to have a pre-existing disease and this group of patients had worse outcome with pOS at 5 years of 29%. PTCL NOS was the largest subtype, with 53 patients, followed by extranodal NK/T-cell lymphoma, nasal type (n = 21), hepatosplenic T-cell lymphoma (n = 16) and subcutaneous panniculitis-like T-cell lymphoma (n = 12). Patients with subcutaneous panniculitis-like T-cell lymphoma had a good outcome with a p OS at 5 years of 83% while patients with hepatosplenic T-cell lymphoma were reported with only pOS of only 16%. There was no clear difference in outcome between patients treated with a B-cell type or a T-cell type of treatment but in general outcome after CHOP/CHOEP appeared to be inferior. CONCLUSION: PTCL is a heterogeneous group of diseases where PTCL NOS is the largest subgroup. Pre -existing medical condition was reported in 25% of the cases and was associated with a poor treatment result. There is a clear need for disease-based treatment recommendation for this group of patients. ; link_to_OA_fulltext