MOC-31 aids in the differentiation of metastatic adenocarcinoma from hepatocellular carcinoma.

Fine-needle aspiration biopsy (FNAB) is frequently used to diagnose mass lesions in the liver. Differentiating metastatic adenocarcinoma from primary hepatocellular carcinoma can be difficult. Despite a number of morphologic criteria, there remain occasional cases in which the cytologic features fail to resolve this differential reliably; in these cases ancillary studies may be useful. Recently, it has been reported that the antibody MOC-31 reliably separates metastatic adenocarcinoma from hepatocellular carcinoma. In this study we examine the utility of MOC-31 in liver FNAB material. Thirty-three archival, alcohol-fixed, paraffin-embedded cell blocks representing 17 cases of hepatocellular carcinomas and 16 cases of metastatic adenocarcinoma were retreived. After protease digestion, the sections were immunostained with the antibody MOC-31 (Dako, Carpinteria, CA) utilizing a modified avidin-biotin complex technique. Only membrane-based reactivity was considered positive. In five cases there was insufficient diagnostic material remaining in the cell block for immunohistochemical staining. Among the remaining cases, MOC-31 reactivity was observed in 10 of 12 metastatic adenocarcinomas and 2 of 16 hepatocellular carcinomas. For metastatic adenocarcinoma the presence of MOC-31 reactivity yields a sensitivity of 83%, a specificity of 87%, a positive predictive value of 83%, and a negative predicitive value of 87%. MOC-31 is useful in separating metastatic adenocarcinoma from hepatocellular carcinoma in FNAB cell block material. Cancer (Cancer Cytopathol)