Biphenotypic Acute Leukemia in Adults

Abstract

Leukemias are characterized by an idiopathic proliferation of a progenitor cell that is committed to a single cell lineage. However, leukemias with dual-lineage differentiation are being described, especially within the pediatric age group. The authors reviewed 118 cases of adult acute leukemia phenotyped by immunofluorescent flow cytometry; 7 cases demonstrated mixed cell lineage. Immunophenotypically these cases were defined by early B-lymphocyte differentiation (TdT, HLA-DR, and CD19) coexpressed with a myeloid receptor (CD13, CD15, or CD33) on the same leukemic cell. Routine cytochemical evaluation demonstrated punctate positivity of the blasts with naphthol AS-D chloroacetate esterase stain in five of seven cases. Cytogenetic analysis revealed structural abnormalities of chromosome 11 in four of the seven cases. Three of these studies showed a break at 11q23-24, the location of the human proto-oncogene ets-1. Clinically, two of these leukemias represented chronic myelogenous leukemia in blast crisis, and all cases behaved aggressively. The authors' data suggest that mixed lineage leukemias are an identifiable subset of adult acute leukemias and are associated with a poor prognosis.

Cytogenetics, molecular and ultrastructural characteristics of biphenotypic acute leukemia identified by the EGIL scoring system

“…10,14 In the present series three cases (13%) revealed new translocations prevalence similar to previous reports. It remains to be seen if any specific gene/genes in these new translocations are of special significance in BAL.…”

“…The incidence of MLL gene rearrangement was also reported to be higher (10-32%). 9,10,14 Although our data showed a lower incidence (13%), however, by combining FISH analysis, the incidence is comparable to published reports (26%). Del(6q) abnormality is known to be commonly associated (10-20%) with childhood T-cell ALL and in adult ALL; the frequency is comparatively lower (5%) and is reported predominantly in young adults (aged 15-40 years).…”

“…Few studies have analyzed the diagnostic and prognostic factors, clinical and biological presentation of BAL patients when compared to other ALs. 5,6,[9][10][11] Herein we have utilized morphological, immunophenotypic, cytogenetic and molecular genetic characteristics to assess whether the EGIL scoring system is sufficiently robust, in practice, to define BAL.…”

Clinical characteristics and outcome of children with biphenotypic acute leukemia

“…In several previous studies the incidence of t(9;22) was high, ranging from 28 to 35%. 7,11,18 However, these were studies involving mixed populations of adults and children, and Philadelphia chromosome-positive leukemias are more common in older age groups. The incidence in our cohort was much lower (3%), since only one patient was found to have this translocation, which is not surprising as our population consisted of children under the age of 14 years old.…”

The 2008 revision of the World Health Organization (WHO) classification of myeloid neoplasms and acute leukemia: rationale and important changes

“…Historically, there has been confusion in the definition, terminology, and the criteria used for subclassification of such cases. [108][109][110] In an attempt to clarify the definition of this group of diseases and to simplify their diagnosis, the 4th edition of the WHO classification not only places acute leukemias of ambiguous lineage in a chapter distinct from those of AML and ALL, but has significantly altered the criteria used to define the largest subset of these cases-those that express antigens of more than one lineage. Cases with no lineage-specific markers are designated as acute undifferentiated leukemia (AUL).…”