Microsatellite instability-high endocervical serous carcinoma manifesting as pulmonary thromboembolism: A case report and review of the literature.

A 53-year-old obese woman was referred because of sudden onset of dyspnea and chronic vaginal bleeding. In addition to severe anemia, multiple pulmonary emboli were identified. Pelvic imaging showed an irregular-shaped mass in the region of the endocervix extending to the lower uterine segment. After successful anticoagulant therapy, followed by placement of an inferior vena cava filter, transabdominal hysterectomy and bilateral salpingo-oophorectomy were performed. An immunopathological study resulted in the diagnosis of endocervical serous carcinoma. After the identification of a high level of microsatellite instability (MSI), an immunohistochemical analysis of mismatch repair (MMR) proteins showed the isolated loss of PMS2. Germline testing of MMR genes showed no mutations, indicating that the high MSI had occurred as a result of sporadic isolated loss of the PMS2 gene expression.