Multiple extramedullary relapses without bone marrow involvement after second allogeneic hematopoietic stem cell...

EMR without BM involvement after allogeneic HSCT is extremely rare, especially in children; only a few cases have been reported. A two-yr-old boy was diagnosed with AML (M4) and underwent allogeneic HSCT in first complete remission with BM from HLA-matched unrelated donor without GVHD. Four yr later, he had a BM relapse and after induction and consolidation chemotherapy, he received a second HSCT from an unrelated donor using peripheral blood stem cells. His second post-transplant course was complicated by extensive chronic GVHD involving the skin, oral cavity, and lungs, which was treated with tacrolimus and corticosteroid. Two yr later, he noticed a mild swelling in the right cheek area. The BM showed a complete remission marrow and a soft tissue biopsy was compatible with granulocytic sarcoma. PET-CT showed multifocal bone involvements. He received chemotherapy, and the chloromas decreased in size. We report a case of diffuse EMR of AML without BM involvement after a second allogeneic HSCT.