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The ultrastructure of hybrid acute leukemia: a study of 15 cases
Yong-Xin Ru1, Hui-Jun Wang, Bing-Xin Yang
1Institute of Hematology & Blood Diseases Hospital, Peking Union College, Tianjin, China.
Abstract:
The objective of this study was to investigate the ultrastructural characteristics of hybrid acute leukemia (HAL). Fifteen cases of HAL were studied by transmission electron microscopy (TEM), focusing on organelles and myeloperoxidase (MPO) reaction of leukemic cells. By TEM, 5 out 15 cases of HAL were consistent with immunophenotyping (3 cases of biphenotypic type, and 2 cases of biclonal type with granulocytes and lymphocytes); 2 cases were suspected as HAL. On other hand, 5 cases of HAL were assigned to ALL, and 2 cases were misinterpreted as M5a and 1 as M4b. Most of the blast cells of biphenotypic HAL showed lymphoid features, except some cases containing MPO positive granules in blasts, while a few cases exhibited monocytic or nonspecific features. TEM offers advantages in the diagnosis of biclonal type HAL and biphenotypic HAL positive for MPO. However, it is difficult to differentiate MPO-negative cases of biphenotypic HAL from ALL and a few cases may be misinterpreted as M5 by TEM.
Insights
Transmission electron microscopy (TEM) aids in diagnosing hybrid acute leukemia (HAL), especially biphenotypic and biclonal subtypes with myeloperoxidase (MPO) positivity. However, differentiating MPO-negative HAL from ALL remains challenging via TEM.
Area of Science:
- Hematology
- Pathology
- Electron Microscopy
Background:
- Hybrid acute leukemia (HAL) presents diagnostic challenges.
- Accurate classification is crucial for appropriate treatment strategies.
- Ultrastructural analysis offers complementary diagnostic insights.
Purpose of the Study:
- To investigate the ultrastructural characteristics of hybrid acute leukemia (HAL) using transmission electron microscopy (TEM).
- To evaluate the utility of TEM in differentiating HAL subtypes and its correlation with immunophenotyping and myeloperoxidase (MPO) reactions.
Main Methods:
- Fifteen cases of HAL were analyzed using transmission electron microscopy (TEM).
- Focus was placed on cellular organelles and myeloperoxidase (MPO) reaction of leukemic cells.
- Results were compared with immunophenotyping data.
Main Results:
- TEM identified 5 out of 15 HAL cases consistent with immunophenotyping (3 biphenotypic, 2 biclonal).
- TEM findings were concordant with immunophenotyping in biphenotypic HAL, with some cases showing MPO-positive granules.
- TEM distinguished biphenotypic HAL from ALL and M5/M4 subtypes, though MPO-negative cases posed differentiation difficulties.
Conclusions:
- Transmission electron microscopy (TEM) is valuable for diagnosing biclonal and MPO-positive biphenotypic HAL.
- TEM aids in identifying specific ultrastructural features correlating with immunophenotype.
- Differentiating MPO-negative biphenotypic HAL from ALL and certain myeloid leukemias solely by TEM remains challenging.
