ABSTRACT
We report elevated serum carcinoembryonic antigen (CEA) in a case of malignant carcinoid tumor of the appendix with liver and lung metastasis. A 55-year-old Thai man was found to have multiple nodules in the liver by ultrasonography. Serum CEA was 7,387.9 ng/mL (normal 0-4.1 ng/mL) leading to a clinical impression of colonic carcinoma with liver metastasis. During the investigation, he developed acute abdomen caused by ruptured acute appendicitis. Malignant carcinoid tumor of the appendix, 1 cm in diameter and located proximal to the ruptured acute appendicitis, was identified. The tumor cells showed trabecular or insular growth pattern, some nuclear pleomorphism but typically fine nuclear chromatin, frequent mitoses and focal necrosis. They were immunoreactive for antibody to chromogranin, neuron-specific enolase, CEA, and cytokeratin. Tumor metastases were discovered in the liver, right lung, mediastinal and right supraclavicular lymph nodes. Electron microscopic study demonstrated pleomorphic neurosecretory granules of the midgut type of carcinoid tumor.