Lineage Switch From Acute Myeloid Leukemia to Acute Lymphoblastic Leukemia: Report of an Adult Case and Review of the Literature

Laboratoire de Cytologie-He´matologie, Hoˆpital Haut-Le´veˆque, CHU Bordeaux, Bordeaux, FranceLineage switch from AML to ALL is an extremely rare phenomenon, and we report thecase of an adult diagnosed with AML at 46 years of age who relapsed with ALL. At initialdiagnosis, blast cell morphology and immunophenotyping were consistent with the di-agnosis of M4-AML. Complete remission was achieved, and the patient underwent au-tologous BMT. At relapse, six months after ABMT, blast cells were different from thoseseen at initial diagnosis, for morphology (L2-ALL), cytochemistry, and immunopheno-typing. The karyotype was normal at both diagnosis and relapse. No evidence of bcr-ablfusion genes was found by RT-PCR. Monoclonal IgH and TCRg gene rearrangement wereevidenced by PCR analysis at relapse but not on blast cells at AML diagnosis. Am. J.Hematol. 65:319–321, 2000.