Gastric Adenocarcinoma With Enteroblastic Differentiation: Lessons From a Rare Case

Abstract

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 α-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.