A healthy 34-year-old man had a mediastinal cyst on the
imaging study. Surgical treatment was performed. The cyst was diagnosed
as a thoracic duct cyst from its anatomic location and contents.
Pathologic examination found it to be consistent with thoracic duct
cyst. Endothelial cells on its luminal surface were identified by an
immunohistologic stain with the factor VIII-related antigen. Twenty-six
cases of thoracic duct cysts have been reported. We report an
additional case and review the previously reported cases. We found that
the ligation of the inferior pedicle of the cyst is essential to
prevent postoperative chylothorax.