SMARCB1/INI1 Is Diagnostically Useful in Distinguishing α-Fetoprotein-producing Gastric Carcinoma from Hepatocellular Carcinoma.

BACKGROUND/AIM: Switch/sucrose non-fermentable (SWI/SNF)-related, matrix-associated, actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1), also named integrase interactor 1, is one of the core subunit proteins in the SWI/SNF ATP-dependent chromatin remodeling complex encoded at chromosomal position 22q11.2. Complete loss of SMARCB1 expression has been reported in various malignant tumors. Immunohistochemistry has demonstrated that SMARCB1 mutation/inactivation correlates well with loss of nuclear SMARCB1 expression. This study investigated SMARCB1 expression in hepatocellular carcinomas (HCCs) and α-fetoprotein (AFP)-producing gastric carcinomas by immunohistochemistry. For comparison, SMARCB1 immunostaining in intrahepatic cholangiocarcinoma (ICC) was also performed.

MATERIALS AND METHODS

Thirty classical HCCs, 30 ICCs and 10 AFP-producing gastric carcinomas were analyzed.

RESULTS

Only one case of HCC had focal labeling of SMARCB1 in the nuclei. Twelve cases of ICC were immunopositive for SMARCB1, with either focal or diffuse reactivity. All AFP-producing gastric carcinomas were immunopositive for SMARCB1 in the nuclei, and the reactivity was consistently diffuse.

CONCLUSION

SMARCB1 is a potential marker for distinguishing metastatic AFP-producing gastric carcinoma from HCC.