Carcinoids of the small intestine: a statistical evaluation of 1102 cases collected from the literature.

A total of 1102 cases of jejunoileal carcinoids collected from 516 articles reported by over 35 countries or related areas were evaluated. Among these 1102 cases. 93 cases of Meckel's diverticular and 969 cases of remaining jejunoileal carcinoids could be effectively analyzed. Multiple clinicopathologic aspects were investigated including clinical manifestations, location, depth and size of the lesions related to metastases, immunohistochemistry, electron microscopy, carcinoid syndrome and serotonin activity. Jejunoileal carcinoids were characterized by a male preponderance with an age group older than that in the extraappendiceal gastrointestinal (GI) series. They also had a significantly aggressive malignant nature exhibiting a high metastasis rate particularly evident in small-size lesions with submucosal invasion. A high incidence of argentaffin cell type and carcinoid syndrome with high serotonin activity was also exhibited by jejunoileal carcinoids.