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appendiceal carcinoid tumor

Thursday 1 February 2007

Thought to arise from the subepithelial endocrine cells in the lamina propria and submucosa, appendiceal carcinoid tumors are the most common neoplasms affecting the appendix.

They are most often discovered during the fourth or fifth decade of life as an incidental finding during surgery performed for other reasons.

Most patients with appendiceal carcinoids are asymptomatic, likely because of the location of the neoplasm in relation to the appendiceal base; the vast majority (75%) are located in the distal third of the appendix, where the risk for obstruction is low, with the remainder located in the middle third, and <10% at the base.

In a series of 150 appendiceal carcinoids, Moertel et al. demonstrated that most appendiceal neoplasms were <1 cm in largest dimension, though larger tumors (>2 cm) appeared to be associated with a poorer prognosis and greater patient discomfort.

In fact, >50% of the patients who had large appendiceal carcinoids in one study presented with a clinical picture suggestive of acute appendicitis.

The prognosis for tumors <2 cm in size is quite favorable, because few of these neoplasms metastasize.

The 5-year survival rate overall is approximately 71% (94% for local disease, 85% for regional metastases, and 34% in the presence of distal disease).

Treatment

Tumor size has been shown to be the best predictor of prognosis in patients with appendiceal carcinoid tumors; as such, the surgical management of appendiceal carcinoids depends largely on the size and location of the primary tumor.

According to current guidelines, simple appendectomy is adequate for the treatment of small carcinoid tumors (

Indications for more extensive surgery than simple appendectomy have been shown to include tumor size >2 cm, lymphatic invasion, lymph node involvement, spread to the mesoappendix, tumor-positive resection margins, and cellular pleomorphism with a high mitotic index.

Given that approximately one third of patients with tumors >2 cm in diameter present with or develop nodal and distant metastases, most experts advocate a right hemicolectomy as the appropriate treatment option.

The management of tumors between 1 cm and 2 cm continues to be debated; however, a more aggressive treatment algorithm that includes right hemicolectomy is often employed, especially in younger patients.

Additional prognostic factors (gender and depth of penetration) may be used in choosing between appendectomy and hemicolectomy in these patients.

See also

- carcinoid tumors

  • digestive carcinoid tumors

- appendiceal tumors

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