Gastric mucinous carcinoma with micropapillary carcinoma component: Case report of tumor morphology not previously described in stomach

Micropapillary (MP) carcinoma is an uncommon tumor with a distinct histologic pattern. Although micropapillary carcinoma has been reported in the stomach, the concurrence of mucinous carcinoma and micropapillary carcinoma has not been reported to-date. A 69-year-old gentleman who presented with anemia was found at endoscopy to have a 1.7 cm gastric ulcer which was biopsied and subsequently underwent a partial gastrectomy. There was an ulcerated moderately differentiated adenocarcinoma displaying a micropapillary component within a mucinous adenocarcinoma component and a metastatic MP carcinoma in 1 of 18 lymph nodes. The tumor was immunoreactive for EMA, MUC2, MUC5AC, MUC6, CDX2, and p53 in both mucinous and mucinous-MP carcinoma areas; and negative for CK7, CK20, CA-125, synaptophysin, chromogranin, PD-L1, MMR proteins, and EBV. To the best of our knowledge, this is the first reported case of MP gastric carcinoma in association with mucinous carcinoma.