Background: Colorectal carcinoids are described as low-grade malignancy in the WHO classification. However, the survival is equally poor between carcinoids and adenocarcinomas if the tumors have lymph node metastasis or distant metastasis.
Patients and methods: We reviewed 17 patients with rectal carcinoid, who underwent surgical resection with lymph node dissection at our institution between March 2005 and November 2007. Our criteria for surgical resection were: tumor size of 10 mm or larger and positive resection margin or the presence of lymphovascular invasion in lesions to which endoscopic or surgical local treatment was carried out.
Results: Lymph node metastases were present in 12 patients. Three of them were with tumors less than 10 mm in size, of whom two patients had lymphovascular invasion. In eight out of the 12 with lymph node metastases, preoperative computed tomography (CT) identified lymph nodes of 5 mm or larger in size.
Conclusions: The present study demonstrated that rectal carcinoids with lymph node metastasis are common. Previously reported risk factors of lymph node metastasis in rectal carcinoid such as tumor size > = 10 mm and lymphovascular invasion are useful in predicting lymph node metastasis. In addition, lymph nodes 5 mm or larger in size identified on preoperative CT suggest the presence of metastasis.