Background: The monoclonal antibody B72.3 has been shown to react with several common types of adenocarcinoma. However, the distribution of B72.3 reactivity in adenocarcinomas has not been well-enough defined to determine whether B72.3 immunostaining would be helpful in the diagnosis of adenocarcinoma of unknown origin.
Methods: Formaldehyde fixed, paraffin-embedded tissue from 476 adenocarcinomas from a variety of primary sites were studied using B72.3 and an avidin-biotin complex immunohistochemical technique.
Results: B72.3 immunoreactivity was seen in 75-100% of the adenocarcinomas from the ovary, endocervix, endometrium, distal esophagus/stomach, colon, lung, breast, prostate, pancreas, and bile ducts. Positive reactions were unusual in thyroid carcinomas (7%) and renal cell carcinomas (11%). B72.3 reactivity was not seen in the 20 hepatocellular carcinomas or 4 adrenal cortical carcinomas studied.
Conclusions: B72.3 reacts with a wide variety of adenocarcinomas. Immunostaining with B72.3 may be helpful in excluding hepatocellular carcinoma in certain clinical settings.