A Concurrence of Adenocarcinoma with Micropapillary Features and Composite Glandular-Endocrine Cell Carcinoma in the Stomach

We report a unique case of synchronous double primary gastric cancer consisting of adenocarcinoma components with micropapillary features and composite glandular-endocrine cell carcinoma components. The patient was a 53-year-old man presenting with a 6-month history of epigastric pain and diarrhea. A subtotal gastrectomy was performed. Histologically, one tumor was composed of micropapillary carcinoma components (50%) with tight clusters of micropapillary aggregates lying in the empty spaces, admixed with moderately differentiated adenocarcinoma components. MUC-1 was expressed at the stromal edge of the micropapillary component. The other tumor was composed of atypical carcinoid-like neuroendocrine carcinoma (50%), adenocarcinoid (30%), and adenocarcinoma components (20%). The neuroendocrine components were positive for CD56, synaptophysin, chromogranin, and creatine kinase. The adenocarcinoid components were positive for both carcinoembryonic antigen and neuroendocrine markers (amphicrine differentiation). This case is unique, due to the peculiar histologic micropapillary pattern and the histologic spectrum of adenocarcinoma adenocarcinoid-neuroendocrine carcinoma of the synchronous composite tumor.