Anti-CD10 immunoperoxidase staining of paraffin-embedded acute leukemias: Comparison with flow cytometric immunophenotyping

CD10 is common in B-precursor acute lymphoblastic leukemia (ALL) but is rar e in acute myeloid leukemia (AML). However, until recently, analysis for CD 10 has generally required fresh or frozen tissue. 56C6 is a monoclonal anti body that is now commercially available for the detection of CD10 in routin ely processed paraffin-embedded tissue. Immunoperoxidase stains for CD10 on paraffin-embedded bone marrow core biopsy specimens (B5-fixed, decalcified ) and marrow aspirate clots (formalin-fixed) were compared with flow cytome tric immunophenotyping for CD10 on fresh cell suspensions in 20 cases of AM L and in 30 cases of ALL. CD10 detection by immunohistochemistry agreed wit h CD10 by flow cytometry in 98% (49 of 50) of acute leukemias. The results matched in 100% (20 of 20) of AML. Five percent (1 of 20) of AMLs expressed CD10. Two of the AMLs with monocytoid differentiation were interpreted as negative for CD10 by flow cytometry, although these had nonspecific dim imm unofluorescence for multiple markers, including CD10, and these cases were negative by immunohistochemistry. CD10 detection by immunohistochemistry ag reed with CD10 by flow cytometry in 97% (29 of 30) of ALL. Eighty-four perc ent (21 of 25) of B-precursor ALL and 40% (2/5) of T-lineage ALL expressed CD10 by immunohistochemistry. In 1 Ease of B-precursor ALL, CD10 was dimly positive in 24% of the blasts by flow cytometry but negative by immunohisto chemistry. We conclude that immunohistochemical staining of paraffin-embedd ed tissue, either B5- or formalin-fixed, is an effective method for the det ection of CD10 in acute leukemia. This technique is useful in distinguishin g AML from ALL. Copyright (C) 2000 by W.B. Saunders Company.