Abstract

Background
: This study was designed to investigate gastrointestinal neuroendocrine tumors with an emphasis on their clinicopathological characteristics.
Methods
: Sixty-five cases were reviewed and classified as typical carcinoid (TC), atypical carcinoid (AC), large cell neuroendocrine carcinoma (LCNEC) and small cell carcinoma (SmCC). We performed immunohistochemistry to characterize the expression of the immunoreactivity for synaptophysin, chromogranin, gastrin, somatostatin, thyroid transcription factor-1, p53 and Ki-67.
Results
: Most commonly, the tumors were located in the rectum (54%), followed by the stomach (23%) and colon (9%). Histologically, the tumors were classified as 49 TCs, 4 ACs, 6 LCNECs and 6 SmCCs. Most tumors were stained positive for synaptophysin and/or chromogranin. Four LCNECs and one SmCC were p53-positive. The carcinoids revealed a low level (<5%) of reactivity for Ki-67, while > or =30% of the cells showed reactivity for Ki-67 in the majority of LCNECs and SmCCs. Six patients with metastatic carcinoids were older than those patients without metastasis (64 vs 48 years, respectively, p=0.004). Furthermore, the size of tumors was larger for the patients with metastatic carcinoids than for the patients with nonmetastatic carcinoids (2.3 vs 0.5 cm, respectively, p=0.005).
Conclusion
: Old age, large tumor size and muscle invasion are associated with high grade neuroendocrine tumor and lymph node metastasis for those patients with carcinoids.

• Keywords: Gastrointestinal tract;Carcinoid tumor;Small cell carcinoma;Neuroendocrine carcinoma;p53;Ki-67