Acute Undifferentiated Leukemia or Minimally Differentiated Acute Myeloid Leukemia: Further Emphasis on Molecular Analysis in Leukemia Diagnosis

Acute undifferentiated leukemia (AUL) is a rare subset of acute leukemias, being included in the 2008 edition of the World Health Organization Classification of Tumors of Hematopoietic and Lymphoid Tissues as a special category called ʻacute leukemias of ambiguous lineageʼ, in which the leukemic cells express no more than one membrane marker of any given lineage. We report a rare case of therapy-related acute myeloid leukemia (AML), in which a strict myeloid marker myeloperoxidase (MPO) expression was confirmed by real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis but not immunophenotyping. Although the diagnosis of AUL was initially considered, the lineage of leukemic cells was demonstrated by qRT-PCR analysis. Our observations suggest that molecular analysis of lineage markers may help to establish the diagnosis of acute leukemias.