Hepatocellular oncofetal protein, glypican 3 is a sensitive marker for α‐fetoprotein‐producing gastric carcinoma

AIMS: Glypican 3 (GPC3) is a cell surface heparan sulphate proteoglycan expressed specifically in the fetal liver and malignant neoplasms of hepatocyte lineage. The aim was to evaluate the significance of GPC3 in alpha-fetoprotein (AFP)-producing gastric carcinoma (GC) and other forms of GC. METHODS AND RESULTS: We immunohistochemically evaluated GPC3 expression in representative cases of AFP-producing GC and in a tissue microarray of a consecutive series of GCs with other markers of hepatocyte lineage (AFP, PIVKA-II and hepatocyte antigen, HEP). In a series of 10 cases of AFP-producing GC, we observed immunohistochemical positivity for GPC3, PIVKA-II and HEP in 10, three and three cases in components with a hepatoid pattern and in nine, two and five cases in components with a non-hepatoid pattern, respectively. In a series of 118 cases of GC, we observed positivity for AFP, GPC3, PIVKA-II and HEP in one (0.8%), four (3.4%), six (5.1%) and 26 cases (22%), respectively. GPC3 was observed concurrently with AFP and discordantly with PIVKA-II and HEP. GPC3 positivity was clearly stronger in a larger area compared with immunoreactivity for AFP. CONCLUSIONS: GPC3 is a sensitive marker for AFP-producing GC and its hepatoid component and is therefore useful to identify this aggressive subgroup of GC.