Abutaily et al reported an immunohistochemical approach to distinguishing malignant mesothelioma and pulmonary adenocarcinoma. This allows for efficient use of resources to make the diagnosis. The authors are from University of Southampton in England.
NOTE: Metastases from extra-pulmonary adenocarcinoma were not considered.
Initial evaluation:
(1) PAS stain
(2) TTF-1 and E-cadherin
|
PAS Stain for Mucin |
TTF-1 and E-cadherin |
Interpretation |
|
positive |
NA |
adenocarcinoma |
|
negative |
both positive |
adenocarcinoma |
|
negative |
both negative |
malignant mesothelioma |
|
negative |
one positive, one negative |
indeterminate |
where:
• TTF-1 is evaluated by nuclear staining. E-cadherin is evaluated by membrane staining.
• TTF-1 is positive in 69% of lung adenocarcinomas and 0% of mesotheliomas.
• E-cadherin is positive in 100% of lung adenocarcinomas and 22% of mesotheliomas.
If a diagnosis was not made during the initial evaluation then additional stains were performed.
|
Stain |
Pattern |
Positivity Favors |
Positivity in AdenoCa |
Positivity in Mesothelioma |
|
CEA |
cytoplasm |
adenoCa |
most |
2% |
|
Ber EP4 |
membrane |
adenoCa |
most |
7% |
|
LeuM1 (CD15) |
cytoplasm |
adenoCa |
most |
0% |
|
calretinin |
cytoplasm and nucleus |
mesothelioma |
6% |
80% |
|
thrombo- modulin |
membrane |
mesothelioma |
6% |
53% |
|
N-cadherin |
cytoplasm |
mesothelioma |
26% |
78% |
|
cytokeratin 5/6 |
cytoplasm, pericellular |
mesothelioma |
6% |
63% |
It is important to know the prevalence of each tumor type in the population.
Specialty: Hematology Oncology, Surgery, general, Pulmonology
