Aims This multi-institutional study and a re-evaluation of the TCGA cohort explores the morphological spectrum, genetics and outcome of GI (gastrointestinal) hepatoid tumours, tumours expressing alpha-fetoprotein (AFP) and fetal-type (FT) GI adenocarcinomas.
Methods 44 tumours with evidence of hepatocellular differentiation were evaluated for morphology as well as by immunohistochemistry for AFP, HepPar1, glypican-3 and arginase-1 and by in situ hybridisation for albumin. Three categories were defined: type I (hepatoid: morphological evidence of hepatocellular differentiation), type II (FT GI adenocarcinoma: tubular profiles and subnuclear vacuolisation, resembling fetal intestine) and type III: positive for at least two hepatocyte-specific markers but lacking morphological evidence of hepatocellular differentiation. GI adenocarcinomas in the TCGA cohort were also evaluated (n=829).
Results 18 cases were classified as type I, 19 as FT GI adenocarcinomas and 7 as type III (resembling conventional gastrointestinal carcinomas). Serum AFP was elevated in 92% of cases. 93% of tumours were positive for glypican-3, 90% for albumin and 89% for AFP. Arginase-1 was restricted to 35% of type 1 tumours. TCGA gastric tumours with elevated AFP expression showed morphological features of FT GI adenocarcinoma (70%) and were exclusively MSI stable. TCGA gastric adenocarcinomas with high AFP expression showed inferior survival on univariate and multivariate analysis.
Conclusions FT GI adenocarcinomas show a distinctive morphological and immunohistochemical profile. Gastric adenocarcinomas with elevated expression of AFP morphologically resemble FT GI adenocarcinomas, demonstrate aggressive behaviour, independent of grade and stage, and a distinct genetic profile.
- hepatoid carcinoma
- hepatocellular carcinoma
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Handling editor Cheok Soon Lee.
Contributors All authors made the following contribution. Substantial contributions to the conception or design of the work, or the acquisition, analysis or interpretation of data. Drafting the work or revising it critically for important intellectual content. Final approval of the version published.
Competing interests The work was partially funded by a sponsored research agreement between the authors’ institution and Affymetrix, California, USA.
Ethics approval Partners IRB.
Provenance and peer review Not commissioned; externally peer reviewed.
Correction notice This article has been corrected since it was published Online First. The first author’s name has been corrected.