Biphenotypic acute leukemia with coexpression of CD79a and markers of myeloid lineage.
Acute leukemias demonstrating immunophenotypic features of more than 1 cell lineage are referred to as acute leukemias of ambiguous lineage in the new World Health Organization classification system. A subtype of leukemia of ambiguous lineage is biphenotypic acute leukemia in which the malignant cell population expresses markers of 2 different lineages, most commonly myeloid and either B- or T-lymphoid lineages. This entity has been defined by a scoring system proposed by the European Group for the Immunological Characterization of Acute Leukemias (EGIL), with various markers assigned a score of 2, 1, or 0.5 depending on their specificity for myeloid or lymphoid lineage. Those cases having a score greater than 2 for the myeloid and either the B- or T-lymphoid lineages are biphenotypic acute leukemia in this system. One marker, CD79a, has been so clearly associated with acute lymphoblastic leukemia (ALL) by some researchers that its expression in the presence of blast markers is considered indicative of B-ALL. We describe an unusual case of acute leukemia meeting the criteria for biphenotypic acute leukemia in which CD79a expression was observed in the blast population.
Frater
John L
JL
Department of Pathology, Northwestern Memorial Hospital and Northwestern University Medical School, Chicago, IL 60611, USA. jfrater@pol.net
Yaseen
Nabeel R
NR
Peterson
LoAnn C
LC
Tallman
Martin S
MS
Goolsby
Charles L
CL
D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD / Q000096:biosynthesis* / Q000276:immunology; D014408:Biomarkers, Tumor / Q000096:biosynthesis* / Q000276:immunology; D051925:CD79 Antigens; D020732:Cytogenetic Analysis / Q000379:methods; D003937:Diagnosis, Differential; D017809:Fatal Outcome; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D016130:Immunophenotyping / Q000379:methods; D015470:Leukemia, Myeloid, Acute / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism; D008297:Male; D010641:Phenotype; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000096:biosynthesis* / Q000276:immunology
D015703:Antigens, CD; D014408:Biomarkers, Tumor; D051925:CD79 Antigens; C497881:CD79A protein, human; D011947:Receptors, Antigen, B-Cell