The clinical utility of the Das-1 monoclonal antibody in identifying adenocarcinoma of the colon metastatic to the liver in fine-needle aspiration tissue.

Background: The cytologic diagnosis of adenocarcinoma in a liver mass usually is straightforward. Identifying where the adenocarcinoma arose from is much more problematic. The Das-1 immunostain is directed against a colon specific antigen and has shown excellent sensitivity and specificity for adenocarcinoma of the colon in surgical pathology studies. In the current study, the authors examined the clinical utility of the Das-1 immunostain in the setting of fine-needle aspiration cell block material from the liver.

Methods: The cell block material from 77 fine-needle aspiration biopsy specimens from the liver were studied. These included 17 hepatocellular carcinomas, 20 colon adenocarcinomas that were metastatic to the liver, and 40 other malignancies, predominantly adenocarcinomas, that were metastatic to the liver from a variety of primary tumor sites. Each case was stained with the Das-1 immunostain using the avidin-biotin complex method and evaluated in a blinded fashion for membranous and/or cytoplasmic staining. The diagnoses were unblinded and correlated with staining and clinical history.

Results: Thirteen of 20 metastatic colon carcinoma samples exhibited immunostaining whereas only 2 of the remaining 57 samples of malignancy exhibited immunostaining.

Conclusions: The results of the current study suggest that the Das-1 immunostain may prove to be helpful in identifying adenocarcinomas in the liver as arising from the colon.