Early adenocarcinoma mixed with a neuroendocrine carcinoma component arising in the gastroesophageal junction: A case report

Abstract

Background: Early adenocarcinoma mixed with a neuroendocrine carcinoma (NEC) component arising in the gastroesophageal junctional (GEJ) region is rare and even rarer in young patients. Here, we report such a case in a 29-year-old Chinese man.

Case summary: This patient presented to our hospital with a 3-mo history of dysphagia and regurgitation. Upper endoscopy revealed an elevated nodule in the distal esophagus 1.6 cm above the GEJ line, without Barrett's esophagus or involvement of the gastric cardia. The nodule was completely resected by endoscopic submucosal dissection (ESD). Pathological examination confirmed diagnosis of intramucosal adenocarcinoma mixed with an NEC component, measuring 1.5 cm. Immunohistochemically, both adenocarcinoma and NEC components were positive for P53 with a Ki67 index of 90%; NEC was positive for synaptophysin and chromogranin. Next-generation sequencing of 196 genes demonstrated a novel germline mutation of the ERCC3 gene in the DNA repair pathway and a germline mutation of the RNF43 gene, a common gastric cancer driver gene, in addition to pathogenic somatic mutations in P53 and CHEK2 genes. The patient was alive without evidence of the disease 36 mo after ESD.

Conclusion: Early adenocarcinoma with an NEC component arising in the distal esophageal side of the GEJ region showed evidence of gastric origin.

Keywords: Adenocarcinoma; Case report; Gastroesophageal junction; Neuroendocrine carcinoma; Next generation sequencing.

Figure 1

A representative upper endoscopic image of a tumor in the gastroesophageal junction. An elevated mucosal lesion was found endoscopically in the distal esophageal side of the gastroesophageal junction. The metaplastic columnar epithelium extended focally in the distal esophagus above the gastroesophageal junction.

Figure 2

Histological findings of poorly differentiated adenocarcinoma mixed with a neuroendocrine carcinoma component. A: Submucosal esophageal glands (arrow) were observed, indicating the distal esophageal location (× 20); B: The area defined by the white rectangle in Figure 2A was enlarged and showed the mixture of moderately (left) and poorly (right) differentiated adenocarcinomas (× 100); C: Adenocarcinoma with a neuroendocrine carcinoma (NEC) component arose in the cardiac mucosa (× 20); D: The area in the black rectangle in Figure 2C exhibited a mixture of adenocarcinoma (right) with NEC (left; × 100); E: The area defined by the black rectangle in Figure 2A was enlarged and demonstrated glandular dysplasia with goblet cells (× 100); F: CDX2 was weakly immunoreactive in moderately differentiated adenocarcinoma and immunonegative in poorly differentiated adenocarcinoma (× 100); G: Mucin 5AC was diffusely immunopositive in poorly differentiated adenocarcinoma and focally immunopositive in moderately differentiated adenocarcinoma (× 100); H: Synaptophysin was diffusely immunopositive in NEC, but immunonegative in adenocarcinoma (× 100); I: The Ki-67 proliferative index was approximately 90% for both the adenocarcinoma and NEC components (× 100); J: p53 was diffusely immunopositive for the adenocarcinoma and NEC components (× 100). All controls stains were adequate.