Goblet cell tumors of the appendix: A review.

Goblet cell tumors are rare tumors of the appendix that exhibit both neuroendocrine and mucinous differentiation. This dual differentiation has led to a controversy regarding the proper classification of these neoplasms as to whether they should be considered neuroendocrine tumors or adenocarcinomas. Multiple grading systems have been proposed that were able to segregate these tumors into prognostically significant groups. Many of these grading systems rely on identifying and/or quantifying the carcinomatous growth pattern. Goblet cell tumors show patchy and focal expression of neuroendocrine markers and are characterized by a mutational profile that is different from both appendiceal adenocarcinomas and neuroendocrine tumors. They exhibit a more aggressive behavior than neuroendocrine tumors, and as such, many authors recommend that they be approached and treated as adenocarcinomas.