Multiple isolated extramedullary relapse of acute promyelocytic leukemia after allogeneic hematopoietic stem cell transplant: a case report and review of literature

Isolated extramedullary disease (EMD) is uncommon, especially in acute promyelocytic leukemia (APL) after allogeneic hematopoietic stem cell transplantation (HSCT). We review the literature and present a 32 year old woman with APL who developed multiple EMDs after allogeneic HSCT within the calvarium, and later found to have various isolated lesions including femur, humerus and thoraco lumbar vertebrae. She was treated with local radiotherapy (XRT) to EMD lesions, all-trans retinoic acid, arsenic trioxide and donor lymphocyte infusion at different time points in her clinical course, without success. Out of reported cases in clinical setting as ours, average onset of isolated EMD is 25 months and median survival 14 months. Effective treatment of isolated EMD after HSCT is not yet clear, but ATO in combination with local XRT, tamibarotene and second HSCT have shown good results in some reported cases, but accumulation of more cases is needed to elucidate optimal therapy in such setting.