[Primary malignant tumor of the appendix: clinicopathological analysis of 22 cases].

Objective: To investigate the clinicopathological and immunohistochemical features of primary malignant tumor of the appendix.

Methods: The clinical data were reviewed; and histopathological and immunohistochemical features were analyzed in 22 cases with primary malignant tumor of the appendix.

Result: In 22 cases of primary malignant tumor of the appendix, 19 cases were carcinoid and 3 were adenocarcinoma. Immunohistochemistry showed that the carcinoid was positively reacted to the neuroendocrine markers, and the adenocarcinoma was negatively reacted to the neuroendocrine markers.

Conclusion: Immunohistochemistry is useful in diagnosis of primary malignant tumor of the appendix, a rare type of cancer.