[Subacute myelogenous leukemia with Phildelphia chromosome]

Twenty-five cases of a special pattern of chronic myeloid leukemia characterized, at the first evaluation, by excessive amount of blasts in blood or bone marrow (myeloblasts greater than or equal to 20%), Ph1 chromosome, and short evolution (median survival = 14,5 months) are reported. Age, spleen volume, white blood cell count are in keeping with those found in usual chronic myeloid leukemia (C.M.L.). However, clinical course is more severe with fever, bone pains, and anemia. Myelogibrosis, high circulating basophil polymorphonuclear count, platelet and megacaryocyte abnormalities (in morphology and number) are frequently associated with blastic excess. Subacute myeloid leukemia Ph1 positive (L.M.S. Ph1+) is proposed as an appellation for these cases in order to distinguish them from chronic myelocytic leukemia (C.M.L.) and other subacute myelogytic leukemias. The association of Ph1 chromosome excess of blasts and bone marrow fibrosis distinguishes L.M.S. Ph+ from: 1 degree C.M.L. with myelogibrosis; 2 degrees unusual cases of Ph1 positive myelofibrosis with myeloid metaplasia (M.M.M.); 3 degrees h1 positive acute leukemia. Forms of L.M.S. Ph+ with heavy blastic involvement are probably transitional cases with Ph1 acute myeloblastic leukemia. Prognosis is poorer than in C.M.L. but better than in acute blastic crisis occurring after chronic phase, which can be very similar to L.M.S. Ph1+, when seen for the first time.