Over the last 15 years, various oncology groups throughout the world have used the PRETEXT system for staging malignant primary liver tumours of childhood. This paper, written by members of the radiology and surgery committees of the International Childhood Liver Tumor Strategy Group (SIOPEL), presents various clarifications and revisions to the original PRETEXT system.

This is part two of a two-part state of the art--hepatoblastoma. International hepatoblastoma specialists were brought together to highlight advances, controversies, and future challenges in the treatment of this rare pediatric tumor. Pretreatment extent of disease (PRETEXT) is a grouping system introduced as part of the multicenter international childhood liver tumors strategy group, SIOPEL-1, study in 1990. The system has been refined over the ensuing years and has now come to be adopted for risk stratification by all of the major pediatric liver tumor multicenter trial groups. PRETEXT is being intensively studied in the current Children's Oncology Group (COG) AHEP-0731 trial in an attempt to validate interobserver reproducibility and ability to monitor response to neoadjuvant chemotherapy, and determine surgical resectability. PRETEXT is now used to identify those patients who are at risk for having an unresectable tumor and who should be referred to a liver specialty center with transplant capability early in their treatment schema. International collaborative efforts in hepatoblastoma have led to increased refinements in the use of the PRETEXT and post-treatment extent to define prognosis and surgical resectability. PRETEXT criteria which suggest a possible need for liver transplantation are discussed in detail.

Background. Posttransplant lymphoproliferative disease (PTLD) is a life-threatening condition the incidence of which in pediatric solid organ transplantation may be related to the immunosuppressive load. It has been suggested that tacrolimus, a new and potent immunosuppressor, causes an increased incidence of this syndrome. Methods. The incidence, early signs, and risk factors for lymphoproliferative disease were reviewed in a cohort of 89 pediatric liver transplant recipients treated with tacrolimus. Results. Eighteen patients (20%) developed a PTLD-16 concomitant to a primary Epstein-Barr virus (EBV) infection and 2 with previous immunity against EBV. Three additional patients had preliminary signs of PTLD concomitant to primary EBV infection, but did not develop individualized lymphoid masses. Six patients died (6.7% of all tacrolimus-treated patients). Mean tacrolimus blood level during the 3 months preceding EBV infection reached 11.8±1.8 ng/ml in PTLD patients versus 9.4±3.4 ng/ml in non-PTLD patients(0.05<P<0.1). Previous OKT3 or antithymocyte globulin treatment was also significantly associated to PTLD. There was no association with age, rejection episodes, steroid-resistant rejection, prior cytomegalovirus infection, HLA mismatch, living donor or cadaveric organ transplantation, United Network for Organ Sharing status at the time of orthotopic liver transplant, and primary or rescue tacrolimus treatment. A significant increase of total γ-globulin level occurred in PTLD patients, and mono/oligoclonal production was significantly associated to PTLD. Conclusion. In EBV-infected pediatric liver transplant recipients, use of OKT3 or antithymocyte globulin and high tacrolimus blood levels are risk factors for a significant increase in the incidence of PTLD. An increase in totalγ-globulin level and appearance of mono/oligoclonal immunoglobulin production are the major preliminary signs of the syndrome.