Regarding the second comment on the foregut cyst by Drs. Song and Suh, the bronchopulmonary foregut malformations are anomalies in the pulmonary development due to abnormal budding of the embryonic foregut and tracheobronchial tree. These anormalies include foregut cysts, bronchogenic cysts, enteric cysts, and neuroenteric cysts. Bronchogenic cysts are congenital lesions, thought to be originated from the primitive ventral foregut and may also be originated from the mediastinum, intrapulmonary area, or less frequently in the subphrenic and intraperitoneal space. The cysts contain mucoid materials and are lined by a ciliated columnar or a cuboidal epithelium. Their walls contain smooth muscles and often cartilage (4-7). We agree with Drs. Song and Suh that the cyst of foregut origin, without seromucinous respiratory glands or cartilage, should be classified as a foregut cyst. However, some have found that even the lining epithelium of a ciliated foregut cyst is identical to the bronchiolar epithelium when the tumor is evaluated by histologic, histochemical and immunohistochemical studies. They suggest that the ciliated foregut cyst is one of the developmental abnormalies that could arise from a bronchiolar bud of the tracheobronchiolar diverticulum (8). Although we agree with Dr. Song and Suh that our case can be depicted as a ciliated foregut cyst, we would like to point out that our case had no connection to the contiguous structure and the lining epithelium did not originate from a metaplastic change but rather was innate in nature, containing a smooth muscle layer. Therefore, it would be reasonable to depict the cyst as a bronchogenic cyst. We hope we can collect more relevant cases to thoroughly investigate the nature and characteristics of the disease.