Regression of syndesmophyte after bone marrow transplantation for acute myeloid leukemia in a patient with ankylosing spondylitis: a case report

INTRODUCTION Disease progression of ankylosing spondylitis has been considered irreversible. However, we report a case of spontaneous regression of syndesmophyte development following allogeneic peripheral blood stem cell transplantation in a patient with acute myeloid leukemia, who was also diagnosed as having ankylosing spondylitis. To the best of our knowledge, this is the first case report presenting the partial radiologic regression of syndesmophytes. CASE PRESENTATION A 39-year-old man with active ankylosing spondylitis achieved clinical remission and partial radiological regression of cervical spine syndesmophytes following a peripheral blood stem cell transplantation for acute myeloid leukemia. Our patient received an allogeneic peripheral blood stem cell transplantation following a pre-transplantation conditioning regimen of total body irradiation and cyclophosphamide. The donor was a human leukocyte antigen-matched 29-year-old man. Our patient has remained asymptomatic and has received no medication for ankylosing spondylitis for nearly three years. CONCLUSIONS Several explanations are proposed for the regression of syndesmophytes and clinical improvement in active ankylosing spondylitis observed in our patient, including changes in bone remodeling and immune reconstitution following stem cell transplantation, the effect of immunosuppressive agents, or fluctuation in the natural course of ankylosing spondylitis although further studies are required. The regression of syndesmophytes in ankylosing spondylitis in this case raises the possibility that stem cell transplantation might contribute to the development of a novel therapeutic strategy for treatment of the disease.