Philadelphia chromosome‐positive acute leukemia: Morphologic and clinical correlations

Twenty‐eight adult patients with Philadelphia chromosome positive (Ph+) acute leukemia were studied to determine if additional chromosomal changes were related to specific morphologic and clinical features. Twenty patients had chronic myeloid leukemia in blast crisis (CML‐BC), three had Ph+ de novo acute nonlymphocytic leukemia (ANLL), and five had de novo acute lymphoblastic leukemia (ALL). Chromosomal abnormalities in addition to a single Ph were noted in 90% of patients with CML‐BC and included a second Ph (five patients), +8 or duplication of part of 8q (five patients), dicentric isochromosome 17 (two patients), and +19 (two patients). Octaploidy with 4 Ph was seen in one patient with megakaryoblastic transformation. One of two patients with a progranulocytic blast crisis had a t(15;17) abnormality. Hypodiploidy was noted in 4 of 20 patients with CML‐BC. Each of the four patients had prominent extramedullary manifestations of blast crisis. All had received intensive chemotherapy prior to the detection of hypodiploidy, and the cytogenetic findings were similar to those often seen in patients with therapy‐related leukemia. An inv(3)(q21q26) was noted in two patients (one CML‐BC, one de novo Ph+ ANLL), one of whom had hypolobulated micromegakaryocytes. Additional cytogenetic abnormalities in de novo Ph+ ANLL (especially +19) were similar to those in CML‐BC. In contrast, the additional karyotypic changes in de novo Ph+ ALL (eg, +4, –7, –20, markers) were those commonly seen in ALL without a Ph and were generally different from those seen in CML‐BC.