Granulocytic sarcoma after stem cell transplantation in a child with biphenotypic leukemia.

Granulocytic sarcoma is an extramedullary tumor composed of leukemic blasts. Isolated granulocytic sarcoma has rarely been reported in children with leukemia undergoing allogeneic stem cell transplantation. We report a case of isolated granulocytic sarcoma arising from the pleura in an 11-year-old girl who was previously treated for biphenotypic leukemia with allogeneic stem cell transplantation. Complete resolution of the tumor was achieved after two inductions with MRC 12 protocol; however, she died of sepsis during the neutropenic period. The unusual presentation, immunophenotypic differences at diagnosis and relapse, and the management options are discussed.