I agree that great caution should be taken in overdiagnosing biphenotypic or hybrid leukemias, especially in the absence of clinical correlation. The following old, but still valuable chapter lays out many of the issues: GR Kitchingman, J Mirro, Jr., and SA Stass, in Molecular Genetics in Cancer Diagnosis, J Cossman editor, Elsevier NY 1990, p223-247. I'd like to point out another oldie but goodie: C-H Pui et al. Myeloid Associated Antigen Expression Lacks Prognostic Value in childhood Acute Lymhoblsatic Leukemia Treated with Intensive Multiagent Chemotherapy. Blood 75:198-202 (1990) They studied 372 children with ALL--16.4% showed myeloid-associated antigen expression. Irene >> I like Kathy Foucar but her book does not represent a consensus. >>After the last ISAC meeting in Rimini, there was a meeting between the >>American consensus group and many European groups and this was discussed >>(there are others who read this list and were there who may want to jump >>in). Bi-phenotypic leukemias are proliferating due to our increased >>sensitivity of detection of antigen expression and of co-expression. We >>just didn't know how many ALL's had coexpression of myeloid antigens. We >>have a clinical knowledge about ALL based upon the less sensitive system. >>Should we start changing the classification of these? MPO +, CD3+ is >>undeniably bi-phenotypic. I don't think the others are. I have had CD13+ >>CLL's (monoclonal light chain's). We know these aren't biphenotypic. Think >>about it. >> >> Maryalice >> >>>Dr. Stetler-Stevenson: >>> >>>This case as you correctly point out, is not unique in being CD45-negative. >>> But I disagree with your interpretation of a B-ALL with aberrant myeloid >>>expression. This case clearly meets criteria for biphenotypic ALL as >>>defined by Foucar in her textbook on bone marrow pathology. MPO expression >>>is not a requirement for classifying as myeloid lineage. >>> >>>> I wouldn't call this one biphenotypic. There is no myeloperoxidase >>>>positivity, correct? It could be an ALL with aberrant expression of >>>myeloid >>>>antigens. >>>> Thank you for sharing this interesting case. >>> >>>> Maryalice >>> >>> >>>David A. Sadler, MD >>>St Joseph Mercy Hospital >>>Ann Arbor MI >> >>Maryalice Stetler-Stevenson >>Director Flow Cytometry Unit >>Laboratory of Pathology, NCI, NIH >> >> >> >> > > > Irene J. Check, Ph.D. Director, Clinical Immunology, Flow Cytometry, and Cytogenetics Evanston Hospital 2650 Ridge Ave Evanston, IL 60201 847-570-2739 (voice) 847-570-1938 (fax)
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