Successful father-to-son stem cell transplantation in a child with hemophagocytic lymphohistiocytosis using a reduced-intensity conditioning regimen.

Objective: Hemophagocytic lymphohistiocytosis (HLH) is an uncommon disorder, usually lethal without allogeneic stem cell transplantation (SCT).

Materials And Methods: We report a 9-month-old boy, the first child of consanguineous parents, diagnosed with HLH and neurological involvement demonstrated by magnetic resonance imaging (MRI), who received an allogeneic SCT from his HLA genetically matched father. Transplant was performed after a reduced-intensity conditioning (RIC) regimen consisting of cyclophosphamide, fludarabine, and melphalan. Graft vs. host disease (GVHD) prophylaxis included cyclosporine a and methotrexate.

Results: An absolute neutrophil count of 0.5 x 10(9)/L was documented on day +20 and a platelet count >20 x 10(9)/L was shown by day 33. Full donor chimerism was showed on day +175. A follow-up brain MRI was reported normal. Twenty months after SCT, the child shows no evidence of HLH or GVHD activity, and has a normal psychomotor development.

Conclusion: Given the reduced toxicity of SCT with RIC, it could represent an attractive transplant method for children with HLH, in whom myeloablation plays no role in disease eradication, and in whom mixed chimerism may be enough to cure the disease.