A T lymphoblastic leukemia/lymphoma that occurs during childhood. The disease is childhood precursor T-lymphoblastic lymphoma/leukemia (Monarch Disease Ontology id MONDO_0004403). Also known as: childhood T lymphoblastic leukemia/lymphoma, paediatric precursor T-lymphoblastic lymphoma/leukemia, pediatric precursor T-lymphoblastic lymphoma/leukemia, precursor T-lymphoblastic lymphoma/leukemia of childhood.