Distant metastasis from a carcinoid tumor of the appendix less than one centimeter in size

The presentation and management of a patient with liver metastasis from a 0.6 cm carcinoid tumor of the appendix is presented. This is the first documented case of distant metastasis from a carcinoid of the appendix less than 1 cm in size. Histopathologic, immunohistochemical, and electron microscopic studies support the appendiceal carcinoid as being the primary neoplasm. Invasion of the mesoappendix was the only finding to suggest potentially aggressive behavior. We reviewed the literature and found 414 previously reported cases that provided complete information regarding tumor size, mesoappendiceal invasion, and presence of metastasis. For the entire group the frequency of metastasis was related to tumor size greater than 2 cm (p less than 0.0001) and invasion of the mesoappendix (p less than 0.0001). After dividing the group based on size, mesoappendiceal invasion was related to metastasis in those tumors less than 2 cm in size (p less than 0.0001) but not in tumors larger than 2 cm (p = 0.1538).