Composite (adenocarcinoid) tumors of the gastrointestinal tract.

Tumors of the gut with composite features of both adenocarcinoma and carcinoid have been recognized mainly in the appendix. There also have been isolated reports of similar tumors arising from other parts of the gastrointestinal tract. It is generally concluded that these tumors have better prognosis than adenocarcinomas of the gastrointestinal tract. We reported six patients with composite tumors arising from the stomach in one, small intestine in two, cecum in two, and rectum in one patient. Clinical presentations in each was suggestive of malignancy with extension to either serosa and/or lymph nodes. Metastasis to liver was present in two patients. Histologically, the tumor showed glands with surface microvilli resembling adenocarcinoma and also organoid pattern with neurosecretory granules in cells resembling carcinoid. Two patients died three and nine months after surgery. The clinical presentation, findings at operation, and the postsurgical course of these six patients reveal that these tumors behave more like an adenocarcinoma than carcinoid and do not appear to have a better prognosis than ordinary adenocarcinoma.