Post-transplant lymphoproliferative disorder is a life-threatening complication of solid organ transplantation. In pediatric recipients, PTLD has been reported in 6.4-19.5 of lung, heart and heart-lung transplants, 4-15 of liver transplants and 1.2-10.1 of kidney transplants. Although most lymphomas typically occur in lymph nodes, extranodal involvement is also common. The aim of our study was to determine the site and symptoms of PTLD in children who underwent liver transplantation during 2009-2012 in Liver Transplantation Center of Nemazee Hospital. Material and methods: This study is a cohort study on existing data of children who received liver transplant between Juanury 2009 and December 2012 at Liver Transplant Center of Nemazee Hospital in Shiraz. During the study period, the PTLD occurrence was assessed in follow up visits, if the diagnosis of PTLD was confirmed the affected patient was entered the study and additional information was obtained. The diagnosis of PTLD was considered in patients with fever of undetermined origin, lymphadenopathy, allograft dysfunction, and pulmonary infiltrates. The data was analyzed using SPSS software ver.18. Statistical descriptive methods, Chi square test, and independent t-test, were used for analyzing the data. P value smaller than 0.05 were considered significant. Results: Totally, 203 children undergoing liver transplant surgery were evaluated. The age range of patients was 8 months to 18 years with mean of 8.8±5.6 years old. In our study 17 (8.4) patients developed PTLD. The mean interval between transplantation and PTLD diagnosis was 8.4 ±5.61 months ranging from 4 to 24 months. A total of five patients (2.5) died during the follow-up period and all of them were PTLD affected children (29.4 of PTLD patients). Lymph nodes were the most predominant site involved (64.7), while liver and GI involved in 35.2. Conclusion: The results of this study emphasize the relatively high incidence of PTLD after liver transplantation in children. Because of its impact on patient's outcome and reducing recipient's survival, it is important to minimize this problem by early diagnosis and providing effective treatment
