RISK OF EXTRAMEDULLARY RELAPSE FOLLOWING ALLOGENEIC BONE-MARROW TRANSPLANTATION FOR ACUTE MYELOGENOUS LEUKEMIA WITH LEUKEMIA-CUTIS

Leukemia cutis (LC) is a rare feature of acute myeloblastic leukemia ( AML). Little information is available regarding its prognostic influen ce on post-transplant outcome, In our institution, 202 patients with A ML received an allogeneic HLA-identical marrow transplant from related donors between March 1982 and January 1994, Thirteen patients had pri or leukemic involvement of the skin (leukemia cutis or LC group) while 189 patients did not (non-LC group), There was a higher incidence of patients with the M4-M5 FAB subtypes in the LC group (83%) as compared to the non-LC group (33%), In addition, the percentage of patients tr ansplanted in relapse was also higher in the LC group (69 vs 15%), Whi le there were no differences observed in the rates of relapse post-tra nsplant in the LC and non-LC groups when matched for stage of disease at transplant, the sites of relapse differed markedly, Five of six rel apses in the LC group involved extramedullary sites as compared to onl y six of 38 relapses in the non-LC group (P = 0.002), with a 6-year pr obability of extramedullary relapse of 38.5% in the LC group as compar ed to 3.9% in the non-LC group, This increased probability of extramed ullary relapse was independent of the FAB morphology (50 vs 2% for pat ients with the M4-M5 subtypes in the LC and the non-LC group respectiv ely) and of disease status at the time of transplant, Moreover, only t hree relapses post-transplant involved the skin, all of which were in the LC group, with a probability of skin relapse of 23.1% in this grou p, Patients with AML and leukemia cutis have a remarkable propensity t o relapse in extramedullary sites following marrow transplantation, Th ese relapses occur in the skin as well as other organs. Further invest igations are needed to understand the biological basis of this clinica l feature.