Goblet cell carcinoids at extraappendiceal locations of gastrointestinal tract: An underrecognized diagnostic pitfall

Background Goblet cell carcinoid (GCC) is a clinicopathologically distinctive tumor that typically arises in appendix and metastasizes frequently. Although rare cases of ostensibly primary extraappendiceal GCC (EGCC) have been reported, the distinction from extraappendiceal metastasis of occult appendiceal primary may be problematic and has not been dealt with systematically in literature. Methods We reviewed our combined experience with EGCC at four North American hospitals and reevaluated all EGCC cases published in literature. Results We encountered 16 cases that were initially reported as EGCC. Five cases presented with disseminated abdominopelvic spread, nine cases with mass lesions in stomach, ileum, cecum, ascending colon, hepatic flexure, sigmoid, and rectum. One case was found incidentally in an ascending colon adenomatous polyp. A negative appendix was confirmed in 2 (12.5%) cases, whereas a primary appendiceal GCC was discovered in 4 (25%) cases at a later date, and appendix was not available for review in 10 cases (62.5%). Of 10 cases of EGCC found in literature, the tumor sites included stomach, duodenum, jejunum, ileum, cecum, spelenic flexure, and rectum. Primary appendiceal tumor was excluded histologically in one (10%), grossly in three (30%), and not at all in six (60%). Nine of our cases were initially misdiagnosed as signet-ring cell adenocarcinomas. Conclusions True EGCC is extremely rare. GCC found at locations other than appendix are most likely extraappendiceal presentations of appendiceal primary. A thorough review of the pathologic status of appendix should be a mandatory diagnostic criterion and should always be documented in the pathology reports.