Rare Tumours in Children and Adolescents (STEP)

Inclusion Criteria: * Diagnosis of a rare solid tumor * Age at diagnosis: Neonatal period to 18 years (In the case of young adults, registration in the database and/or referral to advisory contact persons within the framework of the competence network can take place upon request and after declaration of consent.) * Information, education, written consent of the patient or the guardian * Not recorded in any of the existing clinical studies/ registers of the German Society for Pediatric Oncology and Hematology (GPOH) Exclusion Criteria: * Registration of the tumor diagnosis in a prospective therapy study/ another clinical registry of the GPOH * Lack of information, explanation and/or written consent of the patient or the legal guardian.