Abstract
BACKGROUND: Thymic mucoepidermoid carcinomas (MECs) are extremely rare malignant neoplasms. We describe a rare case of a MEC with a high histological grade in a patient who survived for more than 20 years after the initial surgery, focusing on the clinical course and recurrence pattern. CASE PRESENTATION: A woman underwent surgical resection of a high-grade thymic MEC at another hospital 21 years ago. At the age of 79, she was referred to our hospital with an abnormal opacity incidentally found on her chest radiograph during a health check-up. After the percutaneous biopsy diagnosed thymic MEC, surgical resection was planned based on imaging findings, considering pulmonary metastasis. Intraoperatively, a large tumor and several nodules were detected within the parietal pleura; furthermore, pleural dissemination of the MEC was diagnosed by intraoperative rapid histological evaluation. We completed an exploratory thoracoscopic procedure without performing resection. She did not wish to undergo adjuvant therapy after surgery. Currently, the tumor is growing slowly, but the patient is asymptomatic and is being followed up without treatment intervention. CONCLUSION: We encountered a rare case of pleural recurrence 21 years after complete resection of thymic MEC. Whether surgical resection, including volume reduction surgery, should be used as a treatment strategy for thymic carcinoma with dissemination requires further discussion.