Carcinoid tumors arising from Meckel's diverticulum. A clinical, morphologic, and immunohistochemical study.

Carcinoid tumors arising from Meckel's diverticulum are rare. They resemble appendiceal carcinoids to the extent that they are usually small, single, and asymptomatic. However, they have generally been likened to jejunoileal carcinoids because of their considerable metastatic potential. Because of the paucity of documented cases, Meckelian carcinoids, unlike their counterparts in other topographic regions of the gastrointestinal tract, have hitherto not been systematically investigated with the use of immunohistochemical techniques. In this study, the immunophenotype of four Meckelian carcinoids was determined and comparatively evaluated against that of the corresponding mucosal epithelial endocrine cells. The results show that the immunohistochemical profile of Meckelian carcinoids is more akin to that of jejunoileal rather than that of appendiceal carcinoids. Despite the lymph node metastasis in one case, there were no complications attributable to any of the carcinoid tumors after a mean follow-up period of 10.2 years; this favorable prognosis is reminiscent of appendiceal carcinoids.