Case of Appendiceal Goblet Cell Adenocarcinoma With Gastric Metastasis.

Goblet cell adenocarcinoma (GCA) is a rare appendiceal neoplasm that typically metastasizes to the peritoneum and pelvic organs, with no reported gastric involvement. We report a 72-year-old man with multiple comorbidities presenting with recurrent small bowel obstruction. Imaging revealed a cecal and a gastric mass; colonoscopy confirmed poorly differentiated right-sided adenocarcinoma. Surgical resection with intraoperative biopsies identified high-grade appendiceal GCA infiltrating the cecum, mesentery, and gastric wall. Immunohistochemical staining showed cytokeratin 7 negativity and cytokeratin 20 positivity, suggesting an appendiceal origin. Endoscopic ultrasound-guided fine-needle aspiration of the gastric lesion confirmed gastric metastasis, demonstrating identical morphology and immunoprofile, thus expanding the metastatic spectrum of GCA.