Appendiceal metastasis of gastric cancer clinically masquerading acute appendicitis: possible route of metastasis

Cancer metastasis to appendix vermiformis is rare. We here report a case of appendiceal metastasis of gastric cancer, which was incidentally discovered in the appendix resected as acute appendicitis. A 65-year-old man, who had undergone distal gastrectomy for poorly differentiated adenocarcinoma 2 years before, complained of lower abdominal pain. Physical examination and laboratory tests clinically suggested acute appendicitis. Macroscopically, the serosal surface of the resected appendix was hyperaemic and white-coated. These findings were compatible with the clinical diagnosis. However, histological examination revealed intra-mural invasion of poorly differentiated adenocarcinoma. The appendix serosal and mucosal surfaces were spared from cancer involvement. As the morphological appearance of adenocarcinoma and associated extensive lymphatic invasion was similar to those seen in the primary gastric cancer, the adenocarcinoma observed in the appendix was diagnosed as a metastasis. Possible routes of metastasis to the appendix from stomach were discussed with a brief review of relevant literature.