[Müllerian Cyst of the Posterior Mediastinum].

Müllerian cyst is rarely reported in the literature. Here, we reported a rare case of Müllerian cyst of the posterior mediastinum. The patient was a 46-year-old woman who was found to have an abnormal shadow on chest X-ray film at medical examination and was followed up as suspected of bronchogenic cyst. One year later, the lesion increased and she was referred to our hospital for surgery. Chest computed tomography demonstrated a 36 mm diameter cystic tumor in front of the right 4~5 thoracic vertebra level. We performed thoracoscopic surgery for diagnosis and treatment. Histopathological examination revealed that the cyst wall was covered with a layer of columnar epithelium. In addition, the estrogen receptor was found to be positive in the epithelia by immnunohistology and the pathological diagnosis was a Müllerian cyst. Müllerian cyst have been reported in the literature to be associated with gynecological disorders or obesity. The present case was found to have ovarian enlargement, which has been carefully followed up.