Isolated extramedullary relapse presenting as granulocytic sarcoma after bone marrow transplantation: A single center experience

Abstract

Background: Granulocytic sarcomas are rare extramedullary solid aggregates of malignant myeloid precursor cells. Granulocytic sarcoma after bone marrow transplantation (BMT) is rare. We found 2 cases of post-transplant granulocytic sarcoma out of 121 patients (1.7%) who underwent allogeneic bone marrow transplantation for acute myeloid leukemia (AML) at our institution between 1977 and 2005. Case 1: A 45-year-old male was diagnosed with AML-M1 in July 2002. He received haplo-identical allogeneic bone marrow transplantation from his son. He suffered minimal chronic graft versus host disease (GVHD). Two years after the bone marrow transplant, the patient presented with features of compressive myelopathy secondary to a large mid-thoracic granulocytic sarcoma. He was treated with surgical decompression and local radiation. Bone marrow done concurrently showed morphological remission with 100% donor chimerism. He was subsequently treated with a mini cord transplant, but ultimately died due to transplant related complications. Case 2: A 23-year-old male was diagnosed with AML-M4 and multiple cytogenetic abnormalities in July 2004. He underwent matched unrelated bone marrow transplantation in January 2005. He was on maintenance immunosuppressive treatment for chronic GVHD. In July 2005, he presented with features of cauda-equina syndrome secondary to a pre-sacral granulocytic sarcoma. He was treated with local radiation. Bone marrow done concurrently showed morphological and cytogenetic remission with 100% donor chimerism. Two months later, due to progressive disease and poor performance status, patient and family decided against further chemotherapy. Discussion: Post transplant granulocytic sarcoma is rare (1.7%). Failure of extramedullary immune surveillance may explain occurrence of such tumors when bone marrow is still free from relapse. Most of the extramedullary relapses have been noted in recipients of allogeneic BMT with minimal GVHD. Our first patient did not have any evidence of GVHD and developed extramedullary relapse after two years of receiving haplo-identical bone marrow transplantation. In contrast, the second patient developed GVHD and developed granulocytic sarcoma relatively early in the post transplant period. Immune evasion might have played a role in the pathogenesis of the tumor in our second patient. Both of them faired poorly underscoring the fact that post transplant granulocytic sarcoma carries a sinister prognosis.