Gastric Adenocarcinoma With Enteroblastic Differentiation: Lessons From a Rare Case

Introduction: Gastric adenocarcinoma with enteroblastic differentiation (GAED), also known as clear cell carcinoma or fetal gut-like adenocarcinoma, is a special type of adenocarcinoma characterized by primitive intestine-like structures. GAED partially overlaps with a-fetoprotein–producing gastric carcinoma (APGC). There is insufficient information on the biologic behavior of GAED, which has a worse prognosis compared with conventional gastric carcinoma (GC). Case presentation: We introduce an 82-year-old man who presented 4 years ago with severe epigastralgia; the patient then underwent distal gastrectomy for a large GC. The patient received an initial diagnosis of well-to-moderately differentiated gastric adenocarcinoma with lymphatic invasion and without nodal involvement, resulting in a TNM classification of T1N0M0, stage IB. Follow-up computed tomography 31 months after the gastrectomy revealed a hepatic lesion. Lateral segmentectomy of the liver was performed for therapeutic diagnosis. Pathology specimens from the resected tissue were characterized by glycogen-rich neoplastic cells with eosinophilic cytoplasm with a focal glandular component on hematoxylin-eosin staining and periodic acid–Schiff staining. By retrospective analysis using immunohistochemical staining, Glypican 3 was partially positive and spalt-like transcription factor 4 (SALL-4) was strongly positive in the resected GC and metastatic hepatic carcinoma, indicating that GAED metastasized to the liver. Conclusions: Although exceedingly rare, surgeons should recognize GAED as one of the special types of GC. Treatment guidelines for GAED have not yet been established; however, pathological confirmation of GAED when encountering an APGC by immunohistochemical staining for Glypican 3 and SALL-4 is essential to recognize its malignant biological behavior unlike conventional GC.