Peritoneal well-differentiated papillary mesothelioma coexisting with endometrial adenocarcinoma mimicking peritoneal carcinomatosis: A case report

ObjectiveWe present a rare case of well-differentiated papillary mesothelioma (WDPM) found incidentally in a 59-year-old woman with endometrial cancer.Case reportA 59-year-old nulliparous obese woman with a past history of hypertension and diabetes mellitus presented with postmenopausal bleeding for 11 months. Two months prior to this admission, an episode of massive vaginal bleeding lasting for a day was noticed by the patient. Hysteroscopy was performed after her visit to our outpatient department. Papillary tumors with active bleeding were found in the uterine cavity. Endometrial biopsy showed adenocarcinoma, endometrioid type characterized by papillary architecture lined by columnar cells with mild nuclear pleomorphism. The patient proceeded to magnetic resonance imaging (MRI), which demonstrated a 6.4 × 5.5 × 4.9 cm intrauterine mass. Her tumor marker levels were elevated (CA 125 87.8 IU/ml, CA19-9160.54 IU/ml). The patient then underwent a staging surgery and final pathology revealed stage IA endometrial cancer. During surgery, multiple nodules were found in the peritoneum, initially considered as tumor metastasis and eventually proved to be WDPM.ConclusionIn conclusion, the simultaneous occurrence of WDPM with endometrial cancer is a rare entity. Although no standardized treatment has been established, WDPMs have a relatively favorable prognosis compared to malignant mesotheliomas.