Tumor-associated glycoprotein expression in salivary gland mucoepidermoid carcinomas: an immunohistochemical study using the monoclonal antibody B72.3.

The monoclonal antibody B72.3 recognizes a mucin-like glycoprotein which is expressed in a variety of human malignancies including adenocarcinomas of the breast, colon, lung, endometrium, pancreas, and ovary. The antibody, an immunoglobulin G (IgG1) subclass monoclonal antibody, was generated from membrane-enriched fractions of metastatic mammary carcinoma. Because the antigen detected by B72.3 is expressed in a broad spectrum of human neoplasms, B72.3 is a potentially useful marker for glandular neoplasms. Despite its potential usefulness, there is only one previous comprehensive study which has examined the distribution of the tumor-associated glycoprotein (TAG-72), as detected by B72.3, in salivary neoplasms. We examined 21 mucoepidermoid carcinomas with the antibody. Twenty (95%) of the 21 carcinomas stained positively. The only carcinoma that did not stain was initially thought to be a high-grade mucoepidermoid carcinoma based on immunohistochemical staining. Further review, however, indicated that this lesion was most likely a pure squamous cell carcinoma, and the absence of TAG-72 antigen expression was helpful in this regard. Among those neoplasms which stained with B72.3, the strongest staining was seen in the low-grade carcinomas. These results suggest that B72.3 may be a useful marker for glandular differentiation in mucoepidermoid carcinomas.