Presently, there is no consensus on the best treatment for relapsed B-cell acute lymphoblastic leukemia/lymphoma after allogeneic hematopoietic stem cell transplantation (allo-HSCT), particularly in patients with extramedullary lesions. There are certain anti-tumor drugs that can be used in case of relapse after allo-HSCT, however, prospective randomized studies directly comparing different chemotherapy and immunotherapy approaches are generally lacking. Retrospective studies exploring therapy for relapsed disease are difficult to compare due to the inhomogeneity of patient populations and the diversity of treatment approaches. In such situations, the treatment choice is influenced by the characteristics of the tumor population, particularly, its immunophenotype, available drugs, and the experience of a healthcare facility and physicians. This clinical case report describes the process of treating a patient with B-lymphoblastic lymphoma and shows the possibility of using donor CD19-specific CAR-T cells as a treatment for isolated CNS relapse after allo-HSCT. The patient's parents gave their consent to the use of their child's data, including photographs, for research purposes and in publications.

Transient abnormal myelopoiesis (TAM) is a unique hematological syndrome specific for neonates with Down syndrome. Clinical and hematological manifestations of ТАМ are similar manifestations of acute leukemia, but they may resolve spontaneously by few weeks/months after birth. Summation trisomy 21 and GATA1 mutation in blast clone is a required element for development TAM. Presentation of this syndrome occurs in the first days of life; clinical manifestations may be absent (“silent” TAM) or even lead to death of fetus and neonate. The main interest in the study of this issue is the fact that after spontaneous regression there in 20% of cases at the age of 3–4 years developing acute megakaryoblastic leukaemia (AMKL). The basic transformation factors TAM to AMKL are unknown. In this article we represent 6 cases of TAM identified in Dmitry Rogachev National Research Center for Pediatric Hematology, Oncology, and Immunology from 2012 to 2019. Parents of these patients gave their agreement to use personal data in research and publications.