Appendiceal Adenocarcinoma Involving the Uterus and Mimicking Primary Endometrial Atypical Gastric-Type Mucinous Proliferation : A Rare Case Report

Gastric/gastrointestinal-type mucious lesion in the endometrium may be mostly primary or cervix gastric-type adenocarcinoma involvement. Gastriointestinal and pancreatobiliary adenocarcinoma involving the endometrium is rare. We report a rare appendiceal adenocarcinoma of a 55-year-old female, involving the uterus, mimicking primary endometrial gastric-type lesion. Endometrial lesion was associated with a polyp, which was composed of significant complex papillary architecture and crowed glands resembling lobular endocervical glandular hyperplasia (LEGH), with cytologically abundant pale eosinophilic cytoplasm and atypical nuclear. Mucinous epithelium cells of endometrial lesion was diffusely positive for MUC6, CK7 and negative for p16, PAX8, ER, NapsinA. This histologic morphology and immunophenotype show gastric-type differentiation. Meanwhile, the appendiceal tumor exhibited conventional intestinal type manifestation but focal invasive adenocarcinoma with abundant pale eosinophilic cytoplasm and focally immunoreactivity for MUC6. On the basis of morphologic and immunoreativity examination of the endometrial and appendix, We believe that the diagnosis of atypical mucinous proliferation of gastric-type of endometrium arising from appendiceal adenocarcinoma can be established. Patient died of disease at 3 months after surgery.