[Appearance of Philadelphia chromosome at relapse of erythroleukemia in a 12-year-old boy].

A 12-year-old boy was referred to our hospital because of anemia and jaundice. On admission bone marrow smears were compatible with M6 classification of the FAB, revealing 74.5% erythroblasts of all nucleated cells and 40% blasts of nonerythroid cells. Karyotype analysis revealed 46, XY. Gene rearrangement within the breakpoint cluster region (bcr) on chromosome 22 was negative at this time. Complete remission was attained by a combination chemotherapy. However, at 10 months of remission, cytogenetic studies of the bone marrow demonstrated Ph1 positive (10%). One month later, the patient fully relapsed with a 75% Ph1 positive karyotype associated with positive bcr. Subsequently, the patient died of refractory leukemia.