Magnetic resonance imaging findings and prognosis of gastric-type mucinous adenocarcinoma (minimal deviation adenocarcinoma or adenoma malignum) of the uterine corpus: Two case reports

Our group previously documented the first, very rare case of primary gastric-type mucinous adenocarcinoma of the uterine corpus. Although this type of endometrial cancer appears to be similar to the gastric-type adenocarcinoma of the uterine cervix, its main symptoms, appearance on magnetic resonance imaging (MRI) and prognosis have not been fully elucidated due to its rarity. We herein describe an additional case of gastric-type mucinous adenocarcinoma of the endometrium and review the relevant literature. The two cases at our institution (Kyoto University Hospital, Kyoto, Japan) involved postmenopausal women with a primary complaint of abnormal genital bleeding. Microscopic examination of the hysterectomy specimens indicated a highly differentiated mucinous adenocarcinoma with a desmoplastic stromal reaction. Immunohistochemistry for HIK1083 and/or MUC6 was positive in both cases, suggesting a gastric phenotype. Both patients were diagnosed at an advanced stage, they relapsed or recurred immediately after adjuvant chemotherapy, and eventually succumbed to the disease. The main symptom of gastric-type mucinous adenocarcinoma of the uterine cervix is watery discharge, whereas abnormal genital bleeding in addition to watery discharge is mainly observed in the mucinous type of endometrial adenocarcinoma. Cystic cavities in the tumor are present on MRI in cases of endometrial origin, and prognosis is very poor due to resistance to chemotherapy. Thus, gastric-type mucinous adenocarcinoma of the uterine endometrium exhibits a clinical behavior that is similar to tumors originating from the uterine cervix, but is associated with distinguishing clinical symptoms. The incidence of gastric-type endometrial adenocarcinoma may be higher than expected.