A Case of Primary Appendicular Small Cell Carcinoma Mixed with Mucinous Cystadenocarcinoma

Abstract

We report the case of rare primary mixed small cell carcinoma and mucinous cystadenocarcinoma of the appendix. An 86-year-old men seen for obstipation and flatulence was found in colonoscopy to have a cecal tumor. Computed tomography showed multiple metastases in both hepatic lobes necessitating emergency ileocecal resection with D2 lymph node dissection based on a diagnosis of ileus due to cecal cancer. The tumor mainly occupied the appendix. The major tumor component was small cell carcinoma. The partly tumor component was mucinous cystadenocarcinoma showing gland formation with focal mucin production. The definitive diagnosis was primary mixed small cell carcinoma and mucinous cystadenocarcinoma of the appendix. The postoperative course was uneventful but, cachexia progressed rapidly, and the men died on postoperative day 54. Histologically the resected tumor was a biphasic lesion consisting of small cell carcinoma mixed with mucinous cystadenocarcinoma. Immunohistochemically, the adenocarcinoma lesion was stained strongly for synaptophysin suggesting that the adenocarcinoma had the potential to become small cell carcinoma.