Extramedullary Relapse of Acute Adult Leukemia Following Allogeneic Stem Cell Transplantation:10 Cases Analysis.

Up to date, the knowledge concerning the predisposing factors, pathogenesis and mechanisms of isolated extramedullary relapse (EMR) of acute leuekmia (AL) has not been well elucidated.

We retrospectively analyzed 215 patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) at our center from 1998 to 2006. All of them were adult AL patients (110 acute myeloid leukemia (AML), 102 acute lymphocytic leukemia (ALL) and 3 acute mixed lineage leukemia). 10 cases (4.7%) experienced relapse of extramedullary sites. Among these 10 patients, there were four male and six female patients with a median age of 25 years (range, 22–38 years). Six patients were AML and four patients were ALL. The median interval from diagnosis to transplantation was 9 months (range, 6–15 months). Five patients had cytogenetics or molecular abnormalities. All the patients were in first CR. All the donors were HLA-identical matched (5 siblings and 5 unrelated donor). Conditioning regimen included BU and CY without total body irradiation (TBI). Graft-versus-host disease (GVHD) prophylaxis is consisted of cyclosporin A, a short-term methotrexate and mycophenolate mofetil.

Ten patients experienced isolated EMR at a median of 10 months (range, 3–28months) after allo-HSCT. Sites of EMR varied widely and included CNS (leptomeninges, brain, retro-orbital tissue and paraspinal tissue), skin, bone, pelvis and breasts. Five patients experienced two or more sites of EMR. The most frequently involved in relapse sites were CNS (4 patients) and skin (3 patients). Three patients subsequently developed bone marrow relapse, two patients in 2 and 3 months after the initial EMR and the third patient in 3 months after the second onset of EMR. The remaining seven patients did not develop bone marrow involvement at a follow-up ranged from 3 to 8 months after the initial EMR. Three patients received donor lymphocytes infusion (DLI) combined with chemotherapy and (or) irradiation, two patients achieved CR and remain free of disease for 25 and 32 months after transplant whereas one died due to the second EMR and the following marrow relapse. Two patients received local surgery in combination with radiotherapy or chemotherapy and both remain free of disease for 7 and 18 months post transplant. Among five patients who were only treated with local irradiation or chemotherapy or supportive care, four died from progressive disease.

The prognosis of EMR is generally considered to be unfavorable. An intensified regimen combined of local interventions with systemic chemotherapy may be benefit for patients.

No relevant conflicts of interest to declare.