Gastric cancer with an unexpected appendix metastasis

What happened, in summary

A 54-year-old woman was diagnosed with gastric adenocarcinoma after gastroscopy found a 3 cm stomach mass. Biopsy showed invasive diffuse-type adenocarcinoma with signet-ring morphology. Staging CT and PET/CT did not identify metastatic disease, and she underwent total gastrectomy with D2 lymph-node dissection.

The gastrectomy specimen showed poorly differentiated mixed intestinal and diffuse adenocarcinoma extending through the gastric wall, with all 27 regional lymph nodes negative. Soon after surgery, she developed abdominal pain from an internal hernia with severe colon distension and perforation. Emergency exploration required an extended right hemicolectomy.

The colon itself showed inflammation rather than cancer, but pathology unexpectedly found poorly differentiated gastric adenocarcinoma involving the appendix. This distant metastasis established Stage IV disease even though it had been missed on the original imaging.

She then received 8 cycles of FOLFOX chemotherapy. Follow-up PET/CT at 6, 12 and 18 months showed no recurrence at the surgical sites, regionally or elsewhere. She remained free of recurrent disease beyond the 18-month scan, giving at least 18 months of NED follow-up after treatment.