Outcome of Allogeneic Hematopoietic Stem Cell Transplantation in a Child with Myelodysplastic Neoplasm with Complex Karyotype and ETV6 Variant: Challenges in Treatment

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only treatment with the potential for cure in patients with myelodysplastic neoplasm (MDS). Nevertheless, disease relapse is the main cause of treatment failure. Due to the rarity of childhood MDS (cMDS), there are few studies showing the impact of cytogenetic alterations and genetic variants on outcomes of allo-HSCT, mainly focusing on clonal chromosomal evolution (CCE) during relapse post-transplant. Here, we describe a 3-year-old boy with cMDS-IB, who evolved to MDS/AML. At diagnosis, the patient showed a complex karyotype with chromosomal abnormalities not yet reported together in the same clone, and likely a pathogenic variant in the ETV6 gene. The patient was treated with HLA-matched sibling HSCT, but unfortunately relapsed after HSCT with clonal cytogenetic evolution. This unfavorable outcome suggests that the treatment of pediatric MDS associated with predictive factors of poor prognosis, such as complex karyotype and ETV6 variant remains a challenge.