Difficult to Distinguish from Goblet Cell Carcinoid of the Appendix and One Case of Primary Signet Ring Cell Carcinoma

We present the case of a 65-year-old male patient who underwent appendectomy for perforated appendicitis. Since the pathological diagnosis of the patient was primary signet-ring cell carcinoma of the vermiform appendix with spread to the appendiceal stump, he also received right hemicolectomy. Postoperative chemotherapy with tegafur/uracil (UFT) was administered. When this case was presented at a regional conference, the diagnosis was corrected to be goblet cell carcinoid. Appendiceal goblet cell carcinoid, a neuroendocrine tumor with features unique to the appendix is a rare type with a group of cells with mucus. Signet ring cells were considered and the reason for the differential diagnosis was difficult to determine. On the basis of the relevant literature, we decided to continue the postoperative medical treatment. Since this case is considered rare, we report it here.