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Expression of muscle actins in diffuse mesotheliomas
I T Kung1, V Thallas, E J Spencer
1Department of Anatomical Pathology, Heidelberg Repatriation Hospital, Victoria, Australia.
Human Pathology
|May 1, 1995
Summary
Sarcomatoid mesothelioma shows myofibroblastic differentiation, expressing muscle-specific actin (MSA) and smooth muscle actin (SMA). MSA positivity in epithelial mesotheliomas may aid differentiation from lung cancers.
Area of Science:
- Oncology
- Pathology
- Cell Biology
Background:
- Ultrastructural studies suggest myofibroblastoid differentiation in sarcomatoid/desmoplastic mesotheliomas.
- Immunohistochemical documentation of muscle actin expression in these tumors is limited.
Purpose of the Study:
- To investigate the immunohistochemical expression of muscle-specific actin (MSA) and smooth muscle actin (SMA) in various mesothelioma subtypes.
- To compare actin expression between mesotheliomas and lung cancers to identify potential diagnostic markers.
Main Methods:
- Immunohistochemical analysis of 10 sarcomatoid, 12 epithelial, and 5 biphasic mesotheliomas for MSA and SMA.
- Comparison with 12 lung cancer specimens.
Main Results:
- All sarcomatoid mesotheliomas were positive for both MSA and SMA.
- Epithelial cells in most epithelial and biphasic mesotheliomas showed MSA positivity, with rare SMA positivity.
- Lung cancers were largely negative for MSA and SMA in epithelial cells, but stromal cells in both mesothelioma and lung cancer expressed these actins.
Conclusions:
- Sarcomatoid mesothelioma exhibits myofibroblastic differentiation, confirmed by positive MSA and SMA expression.
- Positivity for MSA in epithelial mesotheliomas may serve as a valuable diagnostic marker to distinguish them from lung cancers.