後縦隔気管支原性囊胞からの発生が疑われた粘表皮癌

Mucoepidermoid Carcinoma Suspectedly Developed from a Bronchogenic Cyst in the Posterior Mediastinum

気管支原性囊胞は，多くは中縦隔，時に後縦隔に発生する先天性囊胞である．まれに癌化することが知られているが，われわれは後縦隔の気管支原性囊胞から粘表皮癌を発生したと考えられる非常にまれな症例を経験したので報告する．

Mucoepidermoid carcinoma developing from a bronchogenic cyst is extremely rare. We present a case of a 74-year-old man with a cystic mass in the posterior mediastinum detected by chest computed tomography （CT） and magnetic resonance imaging. A bronchogenic cyst or neurogenic tumor was suspected. He did not accept surgical treatment and was followed up at outpatient. Since the enlargement of the mass was shown by chest CT after seven years, the resection of the mass was performed by thoracoscopic surgery, however the cyst wall remained due to the severe adhesion and the residual mucosa was cauterized. The mass was diagnosed as a mucoepidermoid carcinoma by pathology which was likely to develop from a bronchogenic cyst. After postoperative radiotherapy, the patient is well without recurrence 10 months after surgery.