Immunophenotyping of acute lymphoblastic leukemia using immunohistochemistry in bone marrow biopsy specimens

Area of Science:

• Hematology
• Oncology
• Pathology

Background:

• Flow cytometry is the standard for acute lymphoblastic leukemia (ALL) diagnosis and immunophenotyping.
• Immunohistochemical staining (IH) of bone marrow trephine biopsies offers an alternative for immunophenotypic analysis.
• Evaluating the utility of IH in ALL diagnosis is crucial for situations where flow cytometry is limited.

Purpose of the Study:

• To assess the diagnostic and immunophenotyping value of IH in bone marrow trephine biopsies for acute lymphoblastic leukemia (ALL).
• To compare IH results with established methods for classifying ALL subtypes (pre-B, T, and B ALL).

Main Methods:

• Studied 50 de novo ALL cases previously classified by morphology, cytochemistry, and flow cytometry (FC).
• Performed IH on paraffin-embedded bone marrow trephine biopsy sections using antibodies: myeloperoxidase (MPO), terminal deoxynucleotidyl transferase (TdT), CD10, CD20, CD79a, and CD3.
• Classified cases into 37 pre-B ALL, 10 T ALL, and 3 mature B ALL.

Main Results:

• TdT was highly expressed (82% of ALL cases, 95% of pre-B ALL).
• CD79a (68%) and CD10 (65%) were common in pre-B ALL; CD79a was also positive in B ALL (66%).
• CD20 was positive in mature B ALL (66%) but less so in pre-B ALL (22%). CD3 was positive in T ALL (70%) and negative in others. MPO was negative in all cases.

Conclusions:

• Immunohistochemical staining of bone marrow trephine biopsies is a viable method for diagnosing and immunophenotyping acute lymphoblastic leukemia (ALL).
• IH provides valuable immunophenotypic information, especially when flow cytometry is not accessible or feasible.