LETTER TO T H E EDITORS t( 12; 17) (p I I ;q I I) Associated with Biphenotypic Leukemia?
We refer to the suggestion by the United Kingdom Cancer Cytogenetics Group (1992) that t(12;17) (pl1;qll) is a new nonrandom abnormality in acute myeloid leukemia (AML). This is surprising in view of the fact that case 2 arose from a previous acute lymphocytic leukemia (ALL). W e have recently identified two patients with relapsed acute leukaemia with the t(12;17) (p12;qll) (Liu et al., 1992). One patient, a 15-year-old male, had a diagnosis of Sudan Black positive common ALL while the second patient, a 31-year-old male, had acute mixed lineage leukaemia based on expression of both lymphoid and myeloid markers (CD19+ CD22 + CD33 +). It would be useful to include immunophenotyping details in future studies to see whether t( 12; 17) is associated with mixed myeloid and lymphoid features. Finally, t( 12; 17) (pll-l2;qll-l2) has been described in unequivocal lymphoblastic leukaemias (Raimondi et al., 1986; Ghione et al., 1988). Hence, it seems more likely that t(12; 17) (pl1;qll) is associated with bipotential progenitor cell leukaemia rather than with AML.