RESUMO
Objective: To investigate the clinical and pathological features of primary gastric (gastrointestinal)-type mucoglandular lesions of the endometrium. Methods: Eight cases of primary gastric (gastrointestinal)-type mucoglandular lesions of endometrium diagnosed between 2014 to 2022 were retrieved from pathology archives of the Obstetrics and Gynecology Hospital Affiliated to Fudan University, Shanghai, China. The clinical history, pathological sections and follow-ups were analyzed. Results: The eight patients ranged in age from 35 to 67 years, with an average age of 55.5 years. Seven patients were examined for high-risk human papillary virus (HPV) before operation. Only one of them was positive for high-risk HPV52. No cervical mucinous lesions were found in any of the patients. Two cases were invasive gastric (gastrointestinal)-type adenocarcinoma, 2 cases were benign gastric (gastrointestinal)-type mucinous metaplasia, and the other 4 cases were atypical gastric (gastrointestinal)-type mucinous gland hyperplasia. Microscopically, tumor cells showed mucous epithelium with gastrointestinal differentiation. Immunophenotyping showed that MUC6 was diffusely or focally positive in 5 cases, CK20 and CDX2 were positive in 3 cases. And p16 was negative or focally positive in 5 cases and strongly positive in 1 case. ER was expressed in both benign and atypical lesions, and weakly positive or negative in the invasive adenocarcinoma. p53 showed mutant expression in one case and wild-type expression in the rest. HPV in situ hybridization was negative. Conclusions: Primary gastric (gastrointestinal)-type mucoglandular lesions of the endometrium show various forms of gastrointestinal differentiation, which are high-risk HPV independent. Morphology combined with immunohistochemistry is helpful for the diagnosis, which can only be made on exclusion of cervical gastrointestinal glandular lesion, gastrointestinal metastatic carcinoma and the mucinous subtype of endometrioid carcinoma.