OBJECTIVE & AIMS   OBJECTIVE Establish a multi-center,international database with prospective registration of pediatric patients presenting with unresectable primary malignant liver tumors (hepatoblastoma-HB, hepatocellular carcinoma-HCC - including HCC developed on chronic liver disease, epithelioid hemangioendothelioma-EHEM), with a remote data entry system, accessible on-line and worldwide AIMS The aims of the Observatory will be: to fully define the role of primary liver transplantation in the treatment of pediatric HB/HCC and other rare malignancies to identify patients at diagnosis who will need a total liver resection and a transplant to define the optimal timing of liver transplantation to define the potential role of pre-transplant neo-adjuvant and post-transplant adjuvant chemotherapy to correlate the staging according to the PRETEXT system with other staging systems like the conventional tumor-node mentastases system for (adult) liver carcinomas (TNM) and the CCSG/POG staging system to correlate the PRETEXT staging of individual patients at presentation with the PRETEXT staging at the time of transplantation (after neo-adjuvant chemotherapy) and with the anatomic observations made on the resected liver to define the amount of post-transplant immunosuppression needed by these children already immunosuppressed at the time of transplantation due to neoadjuvant chemotherapy to quantify the immunosuppressive status at transplantation by measuring the total lymphocyte count to study the incidence, on the long term, of the additive nephrotoxicity of Cisplatin and calcineurin inhibitors For hepatoblastoma to study the impact of vascular invasion (including either the gross or the histologic involvement of vessels) on the relapse rate and the disease-free,patient survival to study the impact of pulmonary metastases,at presentation,on the relapse rate and the disease-free,patient survival to study the impact of the intrahepatic extent and the multifocality of the tumor on the recurrence rate and the disease-free patient survival For HCC to study the impact of histologic differentiation, gross and histologic vascular invasion, size and number of nodules on the relapse rate and the disease-free,patient survival