Navigating Haploidentical Stem Cell Transplantation in Congenital Amegakaryocytic Thrombocytopenia With Prior Intracranial Bleeding: Report of Two Pediatric Cases

Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare inherited bone marrow failure syndrome caused by biallelic myeloproliferative leukemia (MPL) variants, for which hematopoietic stem cell transplantation (HSCT) is the only curative therapy. We report two children with genetically confirmed CAMT and prior intracranial hemorrhage who underwent haploidentical peripheral blood HSCT with reduced intensity conditioning and post-transplant cyclophosphamide. Individualized management included immunomodulation (bortezomib for alloimmune platelet refractoriness in one child; rituximab for B-cell depletion in the other) and an intensified platelet transfusion strategy to maintain hemostatic stability during the peri-transplant period. Both achieved prompt engraftment, transfusion independence, and sustained donor chimerism without neurological deterioration. These cases demonstrate the feasibility of haploidentical HSCT in high-risk CAMT.