Lack of specificity on monoclonal antibody B72.3 in distinguishing chronic pancreatitis from pancreatic adenocarcinoma

Making the morphologic distinction between chronic pancreatitis and pancreatic adenocarcinoma is a diagnostic challenge in small biopsy specimens and fine-needle aspiration samples. It has been suggested that immunohistochemical evaluation for the tumor-associated glycoprotein-72 antigen recognized by the monoclonal antibody B72.3 may be helpful in this setting. Formalin-fixed, routinely processed, paraffin-embedded tissue from 29 known cases of chronic pancreatitis and 31 cases of pancreatic adenocarcinoma were evaluated for reactivity with monoclonal antibody B72.3 using a standard avidin-biotin complex technique. Positive staining was seen in 26 of 31 adenocarcinomas (84%) and in 6 of 29 cases (21%) of chronic pancreatitis. Although monoclonal antibody B72.3 is more commonly reactive with pancreatic adenocarcinoma than with chronic pancreatitis, too many cases of chronic pancreatitis are reactive with this antibody for it to be useful as a diagnostic adjunct.