B72.3 (monoclonal antibody) is also known as TAG-72, as it reacts with the so-named tumor associated protein.  It is expressed on many carcinoma cells, and is sometimes part of a panel to differentiate lung adenocarcinoma (+) from mesothelioma (=).  It has also been used in cytology effusion specimens.  B72.3 stains in a membraneous and cytoplasmic pattern.  B72.3 is expressed in high percentage of adenocarcinomas compared to extremely rare expression in mesotheliomas.

 

Ordonez, NG discusses the expression pattern of B72.3 in the context of multiple large studies with the expression characteristics highlighted in the table below.  It is important to evaluate the expression pattern in the setting of the differential diagnosis.  As example, renal cell carcinomas do not react with B72.3, and this antibody would not be helpful in a strategy to differentiate a mesothelioma from renal cell carcinoma.

 

Riera, J.R., Astengo-Osuna, C., Longmate, J.A., Barrifora, H.,  The immunohistochemical diagnostic panel for epithelial mesothelioma: a reevaluation after heat-induced epitope retrieval.  Am J Surg Pathol.  1997;21:1409.

 

Ordóñez, N. G. (2005). Immunohistochemical diagnosis of epithelioid mesothelioma: an update. Archives of Pathology & Laboratory Medicine, 129(11), 1407–1414.