Acute leukemia with B-lymphoid and myeloid differentiation associated with an inv(5)(q13q33) in an adult patient

A paracentric inversion in the long arm of chromosome 5, inv(5)(q13q33), was found as a clonal abnormality in a patient with a treatment-resistant biphenotypic acute leukemia with B-lymphoid and myeloid differentiation. This cytogenetic aberration has not been reported previously in biphenotypic acute leukemia, although rearrangements of chromosome bands q13 and q33 have been implicated in the development of several hematologic malignancies. The presence of this aberration as the sole chromosomal abnormality suggests an important role in the pathogenesis of biphenotypic acute leukemia.