Your dilemma, my identity: Unusual immunogenetic profiles of pediatric B cell acute lymphoblastic leukemia.

ABSTRACT

B-cell acute lymphoblastic leukemia (B-ALL) is characterized by CD19 expression, which is one of the most important prerequisites, along with expression of CD10, CD22 and/or CD79a. Rearrangements involving MLL gene are seen in CD10− B-ALL (pro-B cell origin) and t(9;11)(p21;q23) is most commonly reported in acute myeloid leukemia (AML), where it is known to carry very good prognosis in pediatric AMLs and rarely in acute lymphoblastic leukemia (ALL). We report a case of CD10+, CD19− pediatric ALL with rearrangements of MLL gene as a result of t(9;11)(p21;q23), thus conferring a very poor prognosis. The case emphasizes use of comprehensive panel of antibodies for fl ow cytometric immunophenotyping and cytogenetic correlation for correct diagnosis and prognostication. KEY WORDS Acute lymphoblastic leukemia, CD19, MLL gene, t(9;11)(p21;q23)