Synchronous primary neuroendocrine and mucinous epithelial tumors present in the same appendix. Case report of 2 patients

BACKGROUND: Although uncommon, neoplasms of the appendix do exist. The two most common types are neuroendocrine tumors and mucinous appendiceal neoplasms. METHODS: In two patients unusual gross and microscopic findings in an appendectomy specimen were recorded. Special immunocytochemistry studies were used to determine the histologic type of the tumors in the appendix. RESULTS: The clinical features and histopathology of two patients who had both a neuroendocrine tumor and a low grade appendiceal mucinous neoplasm in the same appendectomy specimen were described. Possibilities for the causation and treatment of this unusual condition were discussed. The incidence of this double malignancy was estimated at 2.5 in 1000 appendectomy specimens. CONCLUSION: Although extremely unusual, a neuroendocrine tumor and a mucinous appendiceal neoplasm can exist in the same appendix. This condition is reported in two young patients.