Introduction: Synchronous occurrence of benign cystic mesothelioma and adenomatoid tumor of uterus (UAT) are very rare and few cases have been published in the English literature. They are easily misdiagnosed as malignant by clinicians, due to the lack of reports.
Patient concerns: A case of benign mesothelial combined with uterus adenomatoid tumor (UAT) in a 48-year-old Chinese woman was reported. Our patient presented with abdominal pain and surgery showed a large subserous mass (12.0 × 11.4 × 9.8 cm) combined with a small intramural solid nodule (2.0 × 1.0 × 1.0 cm), and multiple minute neoplastic growth on the ovary.
Diagnosis: Due to the patient's symptoms, pathological findings, she was diagnosed with synchronous occurrence of benign mesothelioma and UAT.
Interventions: We treated her with a total hysterectomy and bilateral adnexectomy.
Outcomes: The patient is now in stable condition, without any signs of recurrence during 1 year of follow-up.
Lessons: Most mesotheliomas are malignant, synchronous occurrence of benign mesothelioma and UAT are extremely rare. And they are often misdiagnosed as malignancy by clinicians. Our case report can improve the awareness of the disease and avoid excessive treatment.