Immunophenotyping of acute lymphoblastic leukaemia in routinely processed bone marrow biopsy specimens
B Toth1, M Wehrmann, E Kaiserling
1Institute of Pathology, University of Tübingen, Germany.
Insights
Immunophenotyping of bone marrow biopsies reliably detects acute lymphoblastic leukemia (ALL) subtypes. A minimum antibody panel is proposed for accurate diagnosis and differentiation from acute myeloid leukemia (AML).
Area of Science:
- Hematology
- Oncology
- Immunohistochemistry
Background:
- Accurate immunophenotyping is crucial for diagnosing acute leukemias.
- Bone marrow trephine biopsy specimens are routinely processed for hematological analysis.
- Distinguishing between acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) is critical for treatment.
Purpose of the Study:
- To evaluate the utility of immunophenotyping on routinely processed bone marrow trephine biopsy specimens for ALL diagnosis.
- To establish a minimal antibody panel for assessing lymphoid lineage and differentiating ALL from AML.
Main Methods:
- 45 bone marrow biopsy specimens with suspected leukemia were analyzed using immunohistochemistry (ABC method).
- A broad panel of 26 antibodies against hematopoietic antigens was employed.
- Specimens were formalin-fixed, paraffin-embedded, and mildly decalcified.
Main Results:
- Immunohistochemistry correctly identified 35 cases of ALL, revising initial diagnoses in some instances.
- Seven cases were reclassified as biphenotypic, mixed, or acute myeloid leukemia (AML).
- Anti-CD10 and beta F1 antibodies were most effective for identifying common ALL (c-ALL) and T-cell ALL (T-ALL), respectively.
Conclusions:
- Immunohistochemical analysis of bone marrow biopsies is a reliable method for detecting ALL subtypes.
- A proposed minimum antibody panel (TdT, CD34, myeloperoxidase, lysozyme, CD10, CD79a, CD20, beta F1) aids in immunophenotyping acute leukemia.
- This approach facilitates accurate diagnosis and differentiation of ALL from AML.
Aims:
To assess the value of immunophenotyping of acute lymphoblastic leukaemia (ALL) in routinely processed bone marrow trephine biopsy specimens and to establish a minimum panel of antibodies to assess lymphoid lineage and enable differentiation from acute myeloid leukaemia.
Methods:
45 routinely processed bone marrow biopsy specimens (formalin fixed, paraffin embedded and mildly decalcified in EDTA) reported to contain leukaemic infiltrates on the basis of cytomorphological and enzyme-cytochemical analysis of bone marrow smears (22 c-ALL, 11 T-ALL, 2 B-ALL, 10 u-ALL (unclassified)) were immunostained by the ABC method with a broad panel of 26 antibodies against various haemopoietic antigens.
Results:
Staining with antibodies directed against myeloperoxidase and lysozyme showed that seven cases were either biphenotypic or mixed leukaemias (2), or of myelogenous origin (acute myeloid leukaemia (AML)-M1 (2); AML-M4 (2); AML-M5a (1)). Five of these seven cases had been diagnosed initially as u-ALL. Three further cases with no compact leukaemic infiltrates were excluded. ALL was confirmed in the remaining 35 cases. Because of revised diagnoses, the total numbers of ALL subtypes changed (23 c-ALL, 8 T-ALL, 2 B-ALL, 2 u-ALL). Immunostaining of more than 10% of blast cells in at least one case was found with 19 of the 26 antibodies. The most sensitive lineage specific antibodies for diagnosis were found to be anti-CD10 for c-ALL (22/23) and beta F1 for T-ALL (6/8). Expression of aberrant antigens was fairly common--for example, 7/23 cases of c-ALL stained with antibodies against T cell associated antigens.
Conclusions:
Immunohistochemical investigation of routinely processed bone marrow biopsy specimens enables reliable detection of ALL subtypes c-ALL and T-ALL. A minimum panel of antibodies, against TdT, CD34, myeloperoxidase, lysozyme, CD10, CD79a, and CD20, and the antibody beta F1, is proposed for the immunophenotyping of acute leukaemia.
