Very-early-stage gastric amphicrine carcinoma with mixed histology: A case report and review of literature.

BACKGROUND

Amphicrine carcinoma is an extremely rare entity. In this article, we report the first known case of very-early-stage amphicrine carcinoma characterized by a mixed growth pattern with multiple pathological components.

CASE SUMMARY: A 59-year-old male patient underwent gastroscopy for abdominal discomfort, which revealed a 1.5 cm elevated lesion on the lower part of the anterior aspect of the gastric body close to the gastric angle. Initial biopsy indicated signet-ring cell carcinoma (SRCC) confined to the mucosa. Following endoscopic submucosal dissection, pathological examination revealed signet-ring cells arranged in both nested clusters and diffuse infiltration demonstrating immunohistochemical positivity for periodic acid-Schiff staining for mucin, chromogranin A, and synaptophysin. The coexistence of these endocrine and exocrine markers supported the diagnosis of amphicrine carcinoma. A mixed growth pattern comprising poorly differentiated adenocarcinoma, neuroendocrine tumor, and SRCC was identified. Whether the amphicrine carcinoma arose directly from multipotent stem cells or differentiation from signet-ring cells remains unclear.

CONCLUSION

Routine neuroendocrine immunohistochemical marker staining for SRCC may improve the diagnosis of amphicrine carcinoma and provide guidance for subsequent treatment.