Acute promyelocytic leukemia is characterized by a reciprocal translocation t(15;14)(q22,q12) and its product, the fusion transcript PML-RARα. This anomaly occurs in an early myeloid committed progenitor and lead to hematopoiesis hiatus and potentially active open leukemia. Thanks to differentiating agents introduced in the early 90's, this leukemia is now associated with a favorable outcome. Extra medullary relapses represent 3-5 % of relapse cases, essentially localized to the central nervous system. We report a primitive promyelocytic sarcoma presenting as a sternal tumor without any medullar involvement.